In a medium mixing bowl add 6 eggs, dill, salt and pepper.
In small bowl add melted butter, milk and flour and mix well until all the lumps are out. Alternatively, instead of this butter and milk mixture you can substitute a 1/4 cup of heavy cream.
Add butter and milk mixture to egg mixture and mix well with a wisk to add some air and mix well.
Heat seasoned cast iron skillet on medium heat and add olive oil. When olive oil is heated add onions and sautee until they become softened and translucent. About 3-5 minutes. Add spinach and stir often until spinach becomes wilted. About 3 minutes. Spread spinach and onions evenly over the bottom of the pan.
Add crumbled feta evenly over top of spinach and onion mixture.
Pour egg mixture evenly over top of spinach and feta bottom tilting the pan to ensure egg mixture spread evenly. Continue to cook on stove top until the edges of the egg mixture are set. About 2 minutes.
Move skillet inside oven and continue to bake for 8-10 minutes or until egg mixture in the centre is set. The eggs will fluff up and look like they may explode or boil over but the eggs will deflate when out of the oven and resting. Place a baking sheet underneath if worried. Check if eggs are set in centre by making a small slit in the centre and if the egg mixture runs out leave the frittata in the oven for a few more minutes.
When done remove from the oven and let sit for 5 minutes. Cut into wedges to serve. If using smaller skillets as I have this mixture divides evenly across 3 mini skillets. Follow same instructions but divide oil, feta, spinach and egg mixture evenly between the 3 mini skillets.
Eat right away or refrigerate for up to 4 days in a sealed container. Eat cold or warm up in the microwave.
Video
Notes
Variation:This recipe can be made into 3 individual servings using personal size skillets. Simply cut the recipe into thirds and use one-third of the recipe for each individual size skillet.21 Day Fix Container Count:1 1/2 red, 1 blue, 1 tsp, 1 green