• Preheat oven to 375 degrees Fahrenheit and spray large 16 x 11 rimmed baking sheet generously with cooking spray.
• Veggies: Preheat large skillet on medium heat and add oil. Add onion and saute for 3 minutes, stirring occasionally. Then add bell pepper and saute for another 3 minutes. Add kale or spinach, a pinch of salt and pepper, and saute for 1 more minute, stirring occasionally.
• Eggs: In a large bowl, whisk the eggs, milk, baking powder, a pinch of salt and pepper. Add cooked veggies, sausage and combine with spatula.
• Pour egg mixture onto previously prepared baking sheet moving sausage and veggies around to even them out. Bake uncovered for 25 minutes.
• Remove eggs from the oven, loosen them up from the edges with spatula and cut into 12 squares (I use same spatula). Then gently separate squares from the baking sheet on the bottom.
• Assembly: Cut 12 pieces of parchment paper 1 inch wider than a bun. Cut 12 pieces of aluminum foil twice wider than a bun. Place egg on the bottom part of bun, top with cheese and then top part of bun. Wrap tightly first in parchment paper followed by aluminum foil.

Reheating:

• Option #1 (crispy): Remove wrapping and bake in preheated oven to 425 degrees F: fresh - 10 minutes, frozen - 15-20 minutes.
• Option #2: Place wrapped sandwich onto preheated panini press and cook for 10 minutes - if fresh, 15 minutes - if frozen.
• Option #3: Remove foil and microwave in 45 seconds increments. Microwaves vary, so you will have to experiment how long.
• Option #4 (crispy): Bake uncovered in a toaster oven – watch closely for time as ovens vary.