Preheat oven to 400°F/ 200°C . Line or grease a muffin tin.
In a small bowl add the zest to the sugar and rub in well.
In a large bowl, sift the almond flour, quinoa flour, brown rice flour, tapioca starch, millet flour, protein powder, baking powder, baking soda, psyllium and salt.
To a small bowl add the protein powder and the lemon curd. Mix them to combine and set aside.
In a large bowl beat together the soft butter and sugar/zest until light and fluffy.
Add the eggs and yoghurt to the butter mix and beat until just combined.
Add the dry ingredients to the wet ingredients, in two or three portions, stirring until just mixed with no loose flour. Stir in the lemon juice and the poppy seeds.
Spoon about a tablespoon of batter into each muffin hole. Add about 1/2 teaspoon of lemon curd in the centre, then top with more batter to cover.
Bake at 400 ℉/200℃ for 10 minutes. Reduce the heat to 350℉/177℃ and bake for a further 8 to 10 minutes or until lightly golden on top. Insert a toothpick at the edge of the muffin to avoid the lemon curd. The tooth pick should come out clean.
Let cool in the pan for 10 minutes, then transfer to a wire rack.