Preheat oven to 175°C / 350°F and line a 12-cup muffin tin. Let cream cheese soften.
Mix cream-cheese swirl: beat 170 g cream cheese + 40 g erythritol + egg yolk until smooth; refrigerate briefly.
Whisk dry ingredients: almond flour + baking powder + cinnamon + salt.
Whisk eggs + 80 g erythritol until slightly thickened; add melted butter, almond milk, and vanilla.
Fold dry into wet until just combined (do not overmix). Batter should be thick but scoopable.
Fill 12 muffin cups ~⅔ full. Drop ~1 tbsp cream-cheese mixture into each, then gently swirl with a skewer.
Bake 18–22 minutes until golden. Cool 8–10 minutes in tin; transfer to rack. Enjoy warm or room temperature.