Chocolate Banana Sorbet

4 ripe bananas, peeled and frozen
1/4 cup cocoa powder
3 tablespoons powdered sugar
1 teaspoon vanilla extract

Combine bananas, cocoa powder, powdered sugar, vanilla extract, and instant coffee in a powerful blender.
Using the tamper, blend until all ingredients are incorporated.
Serve immediately or freeze in a freezer-safe container for 3 hours for a firmer texture.