Preheat the oven to 350 degrees F and line a muffin tray with muffin papers
Whisk the melted butter, coconut milk, eggs, and pure vanilla extract together in a mixing bowl until well-combined.
Add the rest of the ingredients except for the blueberries (almond flour, tapioca flour, sugar-free sweetener, baking powder, sea salt, baking powder, lemon zest, lemon juice and poppy seeds) to the mixing bowl and stir vigorously until well-combined.
Gently fold in the blueberries until combined.
Pour the muffin batter into the muffin tray holes, filling the holes ¾ of the way up.
Bake for 30 to 35 minutes, or until the muffin tops are golden-brown and they test clean.
Allow muffins to cool completely before peeling the papers off and eating.
Notes
*If you aren't keto, replace the sugar-free sweeteners with regular granulated cane sugar and powdered sugar.