Preheat oven to 350°F and line a baking sheet with parchment paper. Set aside.
In a medium bowl, whisk the flour, brown sugar, baking powder, and salt together. Cut the butter into the mixture using a pastry blender or two knives, until a crumby dough forms.
2 cups (296g) gluten free flour blend, ⅔ cup (133g) brown sugar, 1 ½ teaspoons baking powder, ¼ teaspoon salt, 4 tablespoons (57g) unsalted butter
Add the applesauce, oil, and vanilla extract into the dry ingredients and stir. The dough will be slightly dry.
⅓ cup (85g) unsweetened applesauce, 3 tablespoons vegetable or canola oil, 1 teaspoon vanilla extract
Transfer the dough to the prepared baking sheet and, using slightly moist hands, form the dough into a rectangular log and flatten slightly (it should be about ¾ in. thick). Bake for 25 minutes.
Remove sheet from the oven and allow to cool for 15 minutes, then slice diagonally into individual pieces. Flip each piece so that it lays flat on its side. Place back into the oven for 12 minutes. Remove, flip each piece, and bake for another 8 minutes. Cool completely before drizzling with melted chocolate and sea salt.
2 ounces dark or milk chocolate, pinch of sea salt