I always start by preheating my oven to 325°F, since a lower temperature keeps the eggs from turning rubbery. While it heats up, I spray my muffin tin generously with cooking oil spray so nothing sticks later. If I'm using silicone cups, I skip the spray, but I still like to have it on hand just in case.
Next, I add the eggs, cottage cheese, salt, and pepper straight into my blender. I blend everything for about 30 seconds until the mixture looks completely smooth with no visible curds. This step is what gives the egg bites that soft, custardy texture I always look forward to.
Once the base is blended, I pour it into a bowl and gently stir in the spinach, bell peppers, cheddar cheese, and sausage if I'm using it. I try not to overmix here, since I want little pockets of veggies and cheese scattered throughout instead of blending them away completely.
I use a measuring cup or ladle to divide the mixture evenly among the 12 muffin wells, filling each about three-quarters full. I find this leaves just enough room for the eggs to puff up without overflowing onto my oven floor, which has happened to me more than once.
I slide the tray into the oven and bake for 22 to 25 minutes, checking around the 20-minute mark. I know they're done when the tops look lightly golden and a toothpick inserted in the center comes out clean. The egg bites will puff up dramatically and then settle back down as they cool, so don't panic if that happens.
Once baked, I let the egg bites rest in the pan for about 5 minutes before running a butter knife around the edges to loosen them. I transfer them to a cooling rack for a few more minutes, then serve them warm or let them cool completely for meal prep storage.