1. Heat bacon fat over medium-high heat, in a large iron skillet. Add squash, onions, water, salt and pepper ~ saute uncovered until squash is tender and water/squash juices have evaporated, stirring occasionally. Slight browning of the squash is okay, but be careful that it doesn't scorch!
2. Remove from heat ~ cool for 15-20 minutes.
3. NOTE: If you are IMPATIENT (like my daughter), and cannot wait until the squash has cooked dry, and the onions have developed a caramelized flavor, then DRAIN the sauteed squash in a colander!
4. Preheat oven to 350°F.
5. Add beaten eggs and shredded cheese to squash, stirring quickly to combine.
6. Pour into a 13x9 Pyrex casserole sprayed with cooking spray.
7. Bake for 35-45 minutes until set ~ should be browned lightly on the bottom. Casserole will firm-up upon cooling. Serve warm.