Preheat the oven to 400°F (204°C). Slice the bananas into rounds, place them on a foil-lined baking sheet coated with nonstick cooking spray, and bake for 5-10 minutes, turning once, until the outside is deep golden brown. Transfer the bananas to a bowl and mash them with a wooden spoon.

Process the oats in a food processor until they become a flour-like meal. Measure the resulting oat flour and combine it with the whole wheat flour, baking powder, salt, cinnamon, and nutmeg in a large bowl.

Whisk the half and half, Greek yogurt, eggs, melted butter, vanilla, and honey until smooth in a separate bowl.

Create a well in the dry mixture and pour in the wet ingredients. Stir about 10 times, only until the batter is barely combined.

Fold the caramelized bananas into the batter, mixing only about 5 additional times to distribute them.

Transfer the batter to a greased 6 or 12 cup muffin tin. Combine the topping ingredients and spoon the mixture over the muffins.

Bake for 10-15 minutes, until the muffins are slightly puffed and the tops spring back when touched.