Preheat oven to 350°F. Lightly grease an 8-cup jumbo muffin tin with nonstick spray.
Open the can of 8 refrigerated flaky biscuits. Press one biscuit into the bottom of each muffin cup and press the sides up about halfway to form a bowl.
If your cooked chicken is cold, warm the 2 cups of cubed chicken nuggets or fingers briefly in the microwave or on the stove until heated through.
In a small saucepan over low heat or in a microwave-safe bowl, melt the 2 tablespoons butter; stir in the 1/4 cup hot sauce until combined. Toss the warmed chicken in the butter–hot sauce mixture until evenly coated.
Divide 1/4 cup ranch dressing evenly among the 8 biscuit cups (about 1/2 tablespoon per cup) and spread it on the bottom of each biscuit bowl. Reserve the additional 2 tablespoons ranch dressing for drizzling after baking.
Sprinkle about 1/2 tablespoon blue cheese crumbles into each biscuit cup on top of the ranch.
Place about 1/4 cup of the prepared spicy chicken into each biscuit cup on top of the blue cheese.
On top of the chicken in each cup, add another 1/2 tablespoon blue cheese crumbles, then 1 tablespoon grated mozzarella and 1 tablespoon grated cheddar per cup.
Bake in the preheated oven for 15–20 minutes, until the biscuit edges are golden brown and the dough is cooked through.
Remove from oven and cool in the pan for 5 minutes. Carefully remove the biscuit cups from the tin.
Drizzle the reserved 2 tablespoons ranch dressing over the biscuit cups, sprinkle with chopped cilantro, and serve warm.