Preheat convection oven to 325°F (163°C) and line an 8x8-inch baking pan with parchment paper, ensuring overhang for easy removal.

Combine almond flour, erythritol, 1/4 cup melted butter, vanilla, and 1/4 tsp salt in a mixing bowl until a uniform crumbly dough forms.

Press the dough firmly into the bottom of the prepared pan and bake for 12-15 minutes until edges reach a light golden hue. Remove and cool completely at room temperature.

In a heavy-bottomed saucepan over medium-low heat, melt 1/2 cup butter and stir in allulose. Whisk continuously for 5-7 minutes as the mixture undergoes caramelization to a deep amber color.

Slowly whisk in heavy cream and sea salt. Caution: the mixture will steam and bubble vigorously. Simmer for an additional 5-10 minutes until the caramel coats the back of a spoon.

Pour the hot caramel over the cooled crust and refrigerate or freeze for 60-90 minutes until the caramel layer is firm and no longer tacky.

In a double boiler or microwave (30-second bursts), melt the sugar-free chocolate chips with coconut oil until the emulsion is smooth and glossy.

Spread the melted chocolate evenly over the chilled caramel layer. Return to the refrigerator for 30 minutes to allow the chocolate to set.

Using the parchment overhang, lift the block onto a cutting board. Using a heated sharp knife, slice into 16 uniform rectangular bars.