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There’s something about a pan of frosted sugar bars that feels like a birthday party, even on a random Tuesday.
I started making these vanilla sprinkle sugar bars when I got tired of scooping individual sugar cookies. One pan, one batch of dough, and you get the same soft, chewy bite as golden syrup flapjacks without babysitting a cookie sheet.
The dough is a thick, buttery vanilla base studded with sprinkles, pressed into a 9×13-inch pan and baked until the edges turn golden. Once it’s fully cool, a layer of vanilla buttercream and another handful of sprinkles finish the job.
Cut into squares, these hold up well for a lunchbox or a party table. They’re soft in the middle with a bit of chew at the edge.
Why You’ll Love This Recipe
- One bowl dough, no cookie scooping or chilling required
- Soft, chewy centers with golden edges every time
- Vanilla buttercream and sprinkles make it party-ready
- Cuts into 16 bars for easy sharing or freezing
Ingredient Notes
- unsalted butter: Use softened butter for both dough and frosting so it creams smoothly. Cold butter won’t cream properly and leaves a dense bar.
- granulated sugar: Standard white sugar keeps the dough from spreading too thin. Brown sugar makes the bars cakey and darker in color.
- eggs: Room-temperature eggs blend into the batter smoother than cold ones. Cold eggs can make the butter seize slightly.
- vanilla extract: Real vanilla extract gives the cleanest flavor. Vanilla bean paste works too and adds tiny flecks throughout.
- all-purpose flour: Spoon and level the flour instead of scooping it from the bag. Packed flour makes these dry instead of soft.
- baking powder: This gives just enough lift so the bars aren’t dense, without turning them into cake.
- rainbow sprinkles (jimmies): Jimmies hold their color and shape in the oven. Nonpareils bleed and turn the dough a muddy gray-blue.
- powdered sugar: Sift it if it’s clumpy, or the frosting ends up with visible sugar lumps.
- milk: Add it a teaspoon at a time. Too much and the frosting turns thin and slides off the bars.
Soft Vanilla Sprinkle Sugar Bars with Buttercream
Ingredients
Method
- Heat the oven to 175 C / 350 F. Grease a 9x13-inch (33x23 cm) baking pan and line it with parchment, leaving a little overhang on the long sides.
- Beat the softened butter and granulated sugar together for 2 to 3 minutes, until pale and fluffy.
- Add the eggs one at a time, beating well after each. Mix in the vanilla extract.
- Whisk the flour, baking powder, and salt together in a separate bowl. Add to the butter mixture in two additions, mixing on low just until combined.
- Fold in the sprinkles by hand with a spatula. Stir gently so the color doesn't bleed into the dough.
- Press the dough evenly into the pan with a greased spatula or your fingers, pushing it into the corners.
- Bake for 25 to 28 minutes, until the edges are golden and a toothpick in the center comes out with a few moist crumbs, not wet batter.
- Cool the bars completely in the pan on a wire rack, about 60 minutes. Don't frost while they're warm or the buttercream will melt into the dough.
- Beat the softened butter for the frosting until smooth, about 1 minute.
- Add the powdered sugar in two batches, beating on low first, then increasing speed once it's incorporated.
- Beat in the vanilla extract and 2 tablespoons of milk. Add the extra tablespoon of milk only if the frosting is too thick to spread.
- Spread the buttercream evenly over the cooled bars with an offset spatula, then scatter the remaining sprinkles over the top.
- Chill for 15 minutes to set the frosting, then lift the bars out using the parchment overhang and cut into 16 squares.
Notes
- Cool the bars fully before frosting or the buttercream melts into the dough.
- Use jimmies, not nonpareils, so the sprinkles keep their color in the oven.
- Don't overmix once the flour goes in or the bars turn tough.
- Line the pan with parchment and leave an overhang for easy lifting.
Tips for Success
- Press the dough evenly with a greased spatula, much like shaping date syrup sesame bars, so the center bakes at the same rate as the edges.
- Pull the bars at 25 to 28 minutes when the edges are golden and a toothpick shows a few moist crumbs.
- Cool the bars completely, about 60 minutes, before frosting or the buttercream will melt into the dough.
- Use jimmies instead of nonpareils in the dough so the sprinkles don’t bleed color into the batter.
- Chill the frosted bars for 15 minutes before cutting for cleaner, sharper squares.
Variations
- Swap half the sprinkles for mini chocolate chips for a funfetti-chocolate chip hybrid bar.
- Add 1/2 tsp almond extract to the dough for a bakery-style cherry-almond undertone.
- Tint the buttercream with a few drops of gel food coloring to match a birthday theme.
Storage and Reheating
Vanilla sprinkle sugar bars keep well at room temperature for 2 to 3 days in an airtight container. After that, move them to the fridge, where they’ll stay fresh for up to 5 days.
These bars are best eaten cold or at room temperature, not reheated. Warming them softens the buttercream and makes it slide, so skip the microwave.
To freeze, wrap the unfrosted, uncut slab tightly and freeze for up to 2 months. Thaw at room temperature, then frost and top with fresh sprinkles right before serving.
Serving Suggestions
Vanilla sprinkle sugar bars work as a lunchbox treat, a potluck dessert, or a stand-in birthday cake when you don’t want to deal with layers.
Pair them with a cold glass of milk or a scoop of vanilla ice cream for a warmer-weather dessert.
For a party spread, cut them smaller into bite-size squares and set them next to fruit skewers or a tray of cranberry orange oat bars.
FAQ
Why are my vanilla sprinkle sugar bars gummy in the middle?
Gummy centers usually mean the bars came out of the oven too early. Bake for the full 25 to 28 minutes until the edges turn golden and a toothpick inserted in the center comes out with just a few moist crumbs, not wet batter. Every oven runs a little different, so start checking at 25 minutes.
Can I use nonpareils instead of jimmies in this sugar bar dough?
You can, but the colors will bleed and turn the dough a grayish blue as it bakes. Jimmies, the rod-shaped sprinkles, hold their color much better under heat. If you only have nonpareils, save them for the top of the frosting instead of mixing them into the dough.
Can I freeze vanilla sprinkle sugar bars?
Yes, but freeze the bars unfrosted for the best texture. Wrap the cooled, uncut dough slab tightly in plastic and foil, freeze for up to 2 months, then thaw at room temperature before frosting and topping with fresh sprinkles.
What goes well with vanilla sprinkle sugar bars at a party?
A cold glass of milk or a scoop of vanilla ice cream balances the sweetness well. For a dessert table, cut the bars smaller and set them alongside fruit skewers or chocolate-covered pretzels so guests aren’t stuck with just one sugary option.
Are vanilla sprinkle sugar bars gluten-free?
Not as written, since the dough uses all-purpose flour. Swap in a 1:1 gluten-free baking blend and the bars turn out close to the original, though slightly more crumbly. Double check your sprinkles too, since some brands add gluten-containing additives.
What’s the difference between sugar bars and funfetti blondies?
Sugar bars use a butter-and-sugar cookie base with just enough egg to bind, giving a lighter, more cookie-like crumb than milk chocolate semolina bars. Funfetti blondies lean on brown sugar and extra egg for a denser, chewier bite closer to a brownie. Both get sprinkles mixed in, but the texture and bake time differ.
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