Preheat oven to 350.
Lightly grease a 11x7 baking pan with cooking spray and set aside.
Heat the oil and butter in a large non-stick frying pan over medium-high heat.
Add garlic and cook for 30 seconds, or until fragrant, but do not brown.
Add asparagus, season with salt and pepper and cook for 6 to 7 minutes, or until tender, turning asparagus to ensure even cooking. Set aside.
Place the eggs, salt, pepper and flour in a bowl and mix well to combine.
Add cheeses and thyme; continue to mix until thoroughly incorporated.
Transfer egg mixture to previously prepared pan.
Top with asparagus.
Bake for 35 to 45 minutes, or until golden brown and cooked through.
Remove from oven and let stand a few minutes.
Cut and serve with a dollop of plain yogurt on top of each slice.