We made this recipe twice in two days. Yes, it's that good. Not too sweet, great texture. (Also it can be made gluten-free by using Measure for Measure flour and certified oats, in a gluten-free kitchen.)

Flax milk works great. I haven't tried oat milk in this recipe because I've run into trouble with the chemistry of oat milk in breads.

Yield: 24 muffins (or two 9x4 quick breads). (You'll definitely want so many -- store the extras in the freezer for later in the week.)

Ingredients Step
Preheat oven to 350 degrees.
Grease 24 muffin cups, or use liners. (Liners are easier but you'll lose more muffin to them.)
270 g oats Grind in food processor to create flour.
270 g (3 c.) oat flour
240 g (2 c.) AP flour
300 g (1½ c.) sugar
4 t. baking powder
1½ t. salt
1 t. cinnamon
Whisk dry ingredients together.
1½ c. milk, cold
6 eggs, room temperature
⅔ c. oil
2 t. vanilla
Whisk wet ingredients together.
4 T. oats
2 T. sugar
½ t. cinnamon
Stir topping together.
Pour liquid into dry. Stir until there are still dry streaks.
1½ c. blueberries (8-10 oz. by weight) Fold in until just combined.
Spoon level ¼ cups into each muffin well.
Sprinkle topping evenly over the muffins.
Bake until toothpick test comes clean (lightly golden tops, perhaps 23-25 minutes).
Cool on wire rack once cool enough to handle.

Source: Jonathan Brasil at King Arthur