Mash the ripe avocado in a small bowl until smooth.
Add the grated cheese, egg, oat flour, and milk to the bowl with the mashed avocado.
Mix all ingredients together until well combined.
Lightly grease small silicone muffin molds or ramekins.
Spoon the mixture into the prepared molds, filling them about two-thirds full.
Prepare your steamer. Place the filled molds in the steamer basket.
Steam over medium heat for 12-15 minutes, or until the bites are firm to the touch and cooked through.
Carefully remove from the steamer and let cool slightly before serving.
