Preheat the oven to 375 degrees F (190 degrees C). Lightly coat an 8- or 9-inch square baking pan with cooking spray.
Cut each biscuit into quarters and place in a 1-gallon resealable bag. Add sugar and cinnamon and seal the bag. Shake the bag until biscuits are well coated, then empty the bag onto the prepared pan. Drizzle melted butter over top.
Bake in the preheated oven until golden brown, about 22 minutes.
While the cinnamon roll bites are baking, prepare frosting. Combine powdered sugar, milk, softened butter, and vanilla in a bowl and stir until smooth.
Remove cinnamon roll bites from the oven and spread frosting over top immediately.