Sift the almond flour and 1 1/2 cups powdered sugar into a mixing bowl. In a separate bowl, whip the egg whites with an electric mixer until foamy, then gradually add the granulated sugar and continue beating until stiff peaks form. Fold the dry ingredients into the egg whites in two additions until the batter flows smoothly off the spatula.

Add 1 teaspoon vanilla extract during the final folds. Pipe small rounds onto a lined baking sheet and let them rest until a skin forms on top. Bake at 300 degrees Fahrenheit for 15 minutes, then cool completely on the sheet.

Beat the butter with the remaining 1/4 cup powdered sugar and 1 teaspoon vanilla extract until light and fluffy. Spread or pipe the buttercream onto half the cooled shells and sandwich with the remaining shells.

Melt the semisweet chocolate and pipe small cone shapes on parchment to form witch hat tops. Once set, place one hat on each macaron and add a few orange sprinkles around the base.