1 1/2 cups all-purpose flour
1 cup unsweetened Dutch process cocoa powder
1 teaspoon salt
1 cup (2 sticks) unsalted butter, at room temperature
1 cup sugar
1 large whole egg
1 large egg yolk
1 teaspoon vanilla extract
1 1/2 gallons ice cream (single or multiple flavors)
Multicolored sprinkles, for garnish
Finely chopped pistachios, for garnish
Mini chocolate chips, for garnish