Carmelized Onion Pudding

This is easy enough to make gluten free and made a nice side dish on Easter.  I think it could have used more eggs to be more puffy and substantial, but had a great flavor.

• 2 large yellow onions, peeled, sliced and cut into half circles
• 2 tablespoons olive oil
• 2 tablespoons unsalted butter
• 1 teaspoon fresh thyme leaves
• 3 large eggs
• 1 tablespoon  flour
• ¹/₂ teaspoon kosher salt
• ¹/₄ teaspoon ground white pepper
• 1 cup whole milk or 1/2 and 1/2

1. In a large skillet, heat the oil and butter. When melted, add the onions and the thyme. Cook slowly, over medium-low heat, until the onions turn limp and brown.
2. Preheat oven to 350 degrees.
3. Using a mixer, beat the eggs. Add the dry ingredients and mix well over medium speed.
4. Lower the mixer speed and add the cream.
5. Grease a medium-sized gratin dish. Add the onions. Cover with the pudding mixture.
6. Bake 40 minutes or until browned and bubbly.