Prepare an ice bath. Bring water to a boil. Blanch a 20oz of fresh spinach in salted boiling water for 2 mins. Remove and place into an ice bath immediately.
Squeeze as much water as possible from the spinach.
Add eggs and 1/2 cup of spinach to a blender and blend until smooth.
Add semola flour to a kneading surface, make a well in the center. Pour the spinach/egg mixture into the well and begin mixing with a fork. Once it is too hard to mix, switch to your hands and begin to incorporate the rest of the flour and knead until you achieve a smooth dough ball, about 5-10 mins.
Wrap in plastic wrap and let it rest for 30 mins.
After 30 mins, cut the dough into 4 pieces. Take one piece and cover the rest in the plastic wrap so it doesn't dry out.
Using a pasta machine, roll the piece on the first setting a few times folding it over onto itself to work it smooth.
Then move through the settings until you reach your desired thickness. Lasagna sheets should not be too thin. I have a kitchenmaid pasta attachment and I went up to #4 thickness.
Place on a well floured baking sheet and cover while you prepare the filling ingredients. I usually place parchment paper into between the sheets so they don't stick together.