Heat 1 tbsp olive oil to a large skillet. Add as much spinach leaves as will fit in the pan. Stir and cook until wilted. Keep adding more spinach leaves and wilting. Season with a few pinches of salt and ground black pepper. Cool and squeeze any excess liquid out and discard the liquid. Chop up spinach.
Heat oven to 350F/180C
Grease bottom and sides of a 9x13 ceramic/glass baking dish
Crack eggs into a large bowl. Add 1/2 tsp salt (or to taste), cayenne powder, mustard and thyme. Whisk well.
Add milk and whisk. Add cheese and mix well.
Spread ham all over the bottom of the baking dish evenly. Spread spinach evenly on top. Scatter red peppers evenly, then the scallions. Pour egg mixture over the top. Gently move the dish side to side to distribute the egg mixture evenly. Even out the top with a spatula.
Cook in the heated oven for 40-45 minutes, uncovered. Casserole is done when middle is set and a toothpick/knife inserted into the middle comes out clean.
***Substitute any type of cooked ground sausage/meat for the ham. Substitute another color bell pepper if you wish. Adjust salt in dish according to amount of salt in type of meat you're using.