Line an 8x8 inch baking pan with parchment paper and grease it lightly with butter. Set aside on a heatproof surface.

Warm the heavy cream in a small saucepan over low heat until it just begins to steam. Remove from heat and keep nearby.

Combine the granulated sugar and honey in a heavy-bottomed 3-quart saucepan. Cook over medium heat, stirring gently with a silicone spatula until the sugar dissolves completely, about 4 to 5 minutes.

Once the sugar dissolves, stop stirring. Clip your candy thermometer to the side of the pot and increase heat to medium-high. Let the mixture cook undisturbed, swirling the pan occasionally, until it turns a deep amber color.

Slowly pour the warm cream into the caramel in a thin, steady stream - the mixture will bubble aggressively. Stir constantly with the spatula until smooth.

Add the cubed butter and salt. Stir until the butter is fully melted and incorporated. Continue cooking over medium heat, stirring frequently, until the thermometer reads 245 F / 118 C, about 8 to 10 minutes.

Remove the pot from the heat. Stir in the vanilla extract. The mixture will smell deeply of honey and butterscotch.

Pour the caramel into the prepared pan in one smooth motion. Do not scrape the pot sides, as those bits can crystallize.

Let the slab cool at room temperature for at least 2 hours, until firm and fully set. Do not refrigerate during this time.

Lift the slab out using the parchment edges and place on a cutting board. Use a lightly oiled chef's knife to cut into 36 small squares with one firm downward press per cut.

Wrap each caramel in a small square of wax paper and twist the ends to seal. Store in an airtight tin at room temperature.