Mint Chip Ice Cream Cake

Ingredients

• 0.5 teaspoon double-acting baking powder 
• 1.5 cups cake flour 
• 6 pints ice-cream chocolate shell packed softened for 20 minutes ()
• 2 cups chocolate wafers such as nabisco famous crushed
• 20 servings sprinkles 
• 0.3 teaspoon cream of tartar 
• 11 large egg whites 
• 2.5 teaspoons gelatin powder unflavored
• 20 servings drop natural food coloring green
• 4 cups cup heavy whipping cream chilled
• 0.5 teaspoon kosher salt 
• 1 cup powdered sugar 
• 1.8 cups sugar 
• 10 tablespoons butter unsalted cooled melted ()
• 1 teaspoon vanilla extract 
• 0.3 cup vegetable oil 

Equipment

• bowl
• frying pan
• baking sheet
• baking paper
• oven
• whisk
• wire rack
• blender
• hand mixer
• spatula
• offset spatula
• serrated knife

Directions

1. Preheat oven to 350°F. Coat a largerimmed baking sheet (17x13x1") withnonstick spray. Line bottom with a largesheet of parchment paper.
2. Whisk flour, baking powder, and salt in amedium bowl to blend; set aside. Using anelectric mixer, beat egg whites on medium-highspeed in a large bowl until light andfrothy, 1–2 minutes. Increase speed to high;add cream of tartar. With mixer running,gradually add sugar. Beat until meringue issoft and pillowy, is tripled in volume, andmedium peaks form, 8–10 minutes.
3. Using a spatula, gently fold dry ingredientsinto meringue, being careful not todeflate. Once flour is almost incorporated,fold in butter, oil, and vanilla; continuefolding until no dry clumps of flour remain.
4. Pour batter into prepared sheet; smooth top.
5. Bake until cake is light golden brown andsprings back slightly when pressed, 16–19minutes.
6. Transfer to a wire rack and let coolin pan for 15 minutes. Invert cake onto rack;peel off paper and let cool completely.
7. Using a serrated knife, halve cake crosswiseinto 2 smaller rectangles. Cover andfreeze at least 1 hour or up to 5 days ahead.
8. Place 1 cake rectangle on a large platter or cake stand.
9. Spread 1/2 cup ice cream evenly over cake.
10. Sprinkle crushed cookies evenly over.
11. Spread remaining ice cream over, beingcareful to keep cookie layer evenly intact.Top with remaining cake rectangle, pressingslightly to adhere. Using an offset spatula,smooth sides of cake. Freeze until ice creamis firm, about 2 hours.
12. Place 2 tablespoons cold water into a smallheatproof glass or metal bowl.
13. Sprinklegelatin over; let soften, about 10 minutes.
14. Pour water to a depth of 1/2" into a smallskillet set over medium heat.
15. Transfer bowlwith gelatin to skillet; stir until gelatindissolves, about 2 minutes.
16. Remove bowlfrom skillet.
17. Place chilled cream in a large bowl.Using an electric mixer, beat cream whilegradually adding melted gelatin. Beat untilsoft peaks form.
18. Add powdered sugar andcontinue to beat until medium peaks formand whipped cream is soft and pillowy (notstiff or grainy).
19. Add green food coloring toachieve a light mint-green hue, 8–10 drops;fold to blend.
20. Using an offset spatula, spread whippedcream over entire cake, creating dramaticswirls on top. Scatter sprinkles over. Freezeuntil cream is set, at least 1 hour. DO AHEAD:Cake can be made 2 days ahead. Keep frozen.