Prep your pan and oven. Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or grease well.
This batter can stick without liners, so liners are safest.
Mix dry ingredients. In a large bowl, whisk almond flour, coconut flour, baking powder, salt, granulated sweetener, and cinnamon until no lumps remain. Breaking up clumps keeps the crumb tender.
Combine wet ingredients. In a separate bowl, whisk eggs, almond milk, melted butter, and vanilla. Make sure the milk and eggs are not cold, or the butter can solidify.
Make the batter. Pour wet ingredients into dry and stir until just combined.
The batter will be thicker than traditional muffin batter but scoopable. If too thick, add 1–2 teaspoons more almond milk.
Make the cinnamon swirl. In a small bowl, mix the brown-style sweetener (or granulated), cinnamon, melted butter, and a pinch of salt. It should be slightly paste-like.
Layer and swirl. Add about 1 tablespoon of batter to each muffin cup.
Spoon a small amount of the cinnamon mixture on top. Add another spoonful of batter, then another small dollop of cinnamon swirl. Use a toothpick to gently swirl the layers.
Don’t overmix; a few turns are enough.
Bake. Bake for 18–22 minutes, or until the tops are set and a toothpick comes out with a few moist crumbs. Almond flour browns quickly, so watch the last few minutes.
Cool. Let muffins cool in the pan for 10 minutes, then transfer to a rack. Cool fully before glazing, or the glaze will melt.
Make the glaze. Beat cream cheese and butter until smooth.
Mix in powdered sweetener, vanilla, a pinch of salt, and enough almond milk to reach a drizzleable consistency.
Glaze and serve. Drizzle over cooled muffins. For a bakery look, add a little extra cinnamon dusting on top. Enjoy warm or at room temperature.