Heat oven to 350°F (175°C). Lightly grease a mini muffin pan or line with mini liners. This recipe makes about 24 mini muffins.
In a large bowl, whisk oat flour, protein powder, almond flour, baking powder, baking soda, spices, and salt. Break up any protein powder clumps—no dusty pockets allowed.
In a separate bowl, whisk pumpkin, eggs, Greek yogurt, maple syrup, sugar, oil, and vanilla until smooth.
Pour wet into dry and fold with a spatula until just combined. If using add-ins, fold them in now. Batter should be thick but scoopable; if it's cement-level thick, add 1–2 tbsp milk.
Spoon batter into mini cups, filling each about 90% full for a domed top.
Bake 10–13 minutes until tops spring back and a toothpick comes out mostly clean (a crumb or two is fine). Overbaking = sadness.
Rest in pan 5 minutes, then transfer to a rack. They firm up as they cool—resist the urge to judge texture right out of the oven.
While warm, sprinkle with a tiny pinch of cinnamon sugar or a dusting of protein powder mixed with cocoa. Looks fancy, took 10 seconds.