Preheat oven to 180 C / Gas 4. Line one muffin tray with paper cases.
Whisk eggs, coconut oil, coconut sugar, lemon zest and lemon extract together in a bowl. Sift salt, bicarbonate of soda and baking powder together in a separate bowl; stir in ground almonds using a rubber spatula. Mix egg mixture into almond mixture until batter is smooth; fold in blueberries. Scoop up mixture using an ice cream scoop and place in paper cases, filling about 3/4-full.
Bake in the preheated oven until a skewer inserted in the centre comes out clean, 30 to 35 minutes. Cool the muffins.
Mix coconut butter, honey and enough lemon juice together in a bowl until smooth; drizzle over muffins once they have cooled down.
Butter or ghee can be used in place of the melted coconut oil in the muffins.