cake decorating paste:
3 1/2 tbsp unsalted butter (softened)
1/3 cup confectioners' sugar
1 large egg white (at room temperature)
1/2 cup all-purpose flour
1/4 tsp orange gel food color
1/8 tsp red gel food color
whipped egg whites:
3 large egg whites (at room temperature)
1/4 cup granulated sugar
sponge batter:
1 cup almond flour
2/3 cup confectioners' sugar (plus more for sprinkling)
1/3 cup all-purpose flour
3 large eggs plus 1 egg yolk (at room temperature)
1/2 tsp orange gel food color
pumpkin skin ganache:
1 cup heavy cream
2 tbsp pumpkin puree (canned)
1 tbsp pumpkin pie spice
1/4 tsp orange gel food color
255 g white chocolate chips or finely chopped bars
buttercream:
4 tbsp unsalted butter (softened)
1 1/2 cups confectioners' sugar
1 tsp vanilla extract
1/2 tsp green gel food color
assembly:
1/4 cup granulated sugar
2 chocolate rolled wafer cookies
2 disposable piping bags
a 15-by10-inch jelly roll pan
a tea towel
a piping bag fitted with a leaf decorator piping tip (leaf tip #70)
a pastry brush
Serve immediately to delighted guests.