Preheat oven to 350℉. Spray 2, 8-inch dome cake pans with cooking spray and add strips of parchment to the pan for easy removal.
Mix all ingredients in a large bowl and beat on low for about 1 min and scrape down sides of the bowl. Beat on high with a hand mixer for 2 minutes. Pour batter evenly into pans. Bake for 30-35 minutes until a toothpick comes out clean from the center. Cool for 10 minutes and turn out of pans and allow to cool completely.
Frosting
Add cream cheese, butter, and vanilla extract to a stand mixer with a paddle attachment and beat until fluffy. Add powdered sugar slowly and beat until incorporated. Add whipping cream and beat until incorporated. Set aside.
Assembly
Trim the flat sides of the two dome cakes and frost one side generously with frosting. Top with the frosted dome with the other dome to create a sphere. Frost the whole cake with frosting. Chill cake until ready to serve. Note: Cotton candy will shrink up as it sits in air, so make sure to only apply the cotton candy to the cake right before you are ready to serve it. Tear off small tufts of cotton candy and stick them into the frosting to mimic a spider egg sack. Top with a swarm of edible spider cupcake toppers and serve immediately.