For the muffins, defrost and drain the spinach. Finely puree the feta cheese with the hand blender and mix with the spinach. Mix the eggs, oil, buttermilk, salt and pepper together. Mix the flour with the baking powder and stir quickly into the egg mixture. Fold in the feta and spinach mixture by hand. Pour the batter into the muffin tins. Bake at 180 ° C for about 30 minutes.
For the topping, puree the smoked salmon with the lemon juice. Now stir the remaining ingredients together and add the salmon puree. Finally, season with salt and pepper. The topping can now be sprayed onto the muffins. Garnish with some salmon and dill.