Summer Strata with Spinach, Basil & Roasted Garlic Custard

Not too long ago I made this southwest brunch bake for mother's day brunch, but I had initially wanted to make this summer strata. The strata is more work though with caramelizing onions, roasting garlic, washing and cooking spinach, etc whereas the southwest brunch bake is pretty much dump and mix. I don't mind doing the bit of extra work for this strata, but when I had to prepare a few other dishes, I went with the simpler southwest brunch bake! However, this summer strata is super yummy and flavourful, and I'm really happy I tried it out for a weeknight meal. The only thing I'd change is to use less milk, as the bread was a bit soggy for my liking.

Also, I hope you guys didn't miss out on seeing this seriously amazing chile-cheese bread I just posted about. It would be sad if you did because it was one of the best things I've eaten this year!

If this sounds good, you might also like:
Southwest Brunch Bake
Savoury Vegetable Cheesecake
Butternut Squash Casserole
Tomato and Corn Pie

Summer Strata with Spinach, Basil & Roasted Garlic Custard
Adapted from Rebar: Modern Food Cookbook

Serves 8-12

Caramelized Onions
1 tbsp butter
1 tbsp olive oil
4 yellow onions, sliced or diced
1 tsp salt
1/2 tbsp brown sugar
1/2 cup white wine
1/4 cup vegetable stock or water
2 tsp balsamic vinegar
1/4 tsp cracked pepper
1 tsp minced fresh thyme, sage or rosemary

Filling
1 lb sourdough loaf, cut into 3/4" cubes (I think you can use whatever bread you want here)
2 bunches of spinach, wilted, squeezed and chopped
1 recipe caramelized onions
1/2 cup sundried tomatoes (not oil packed)
1/2 cup chopped basil
1/2 cup chopped parsley
1 1/2 cups grated fontina cheese

Custard
6 eggs
3 cups milk (I used 1%, and will use less milk next time)
2 bulbs roasted garlic, mashed
1 tsp salt
1/2 tsp cracked pepper

Caramelized Onions
1. Heat olive oil and butter over medium heat until the butter begins to foam. Add the onions and stir to coat. Add salt and cook for 20 minutes. Stir occasionally.

2. Sprinkle in the sugar and wine and reduce until the liquid has evaporated. Add stock, vinegar, pepper and herbs. Cook gently until the stock is reduced and the onions reach a creamy texture.

Filling and Custard
1. Prepare all of the ingredients for the filling. Soak the sundried tomatoes until soft, strain and chop coarsely.

2. To make the custard, whisk the eggs in a large bowl. Whisk in the milk, cream, mashed roasted garlic, salt and pepper. Stir in the bread cubes, cover and let stand for 1 hour. Stir occasionally to ensure that all of the bread is evenly soaked. Stir in the remaining ingredients, reserving half of the grated cheese.

3. Heat the oven to 350F. Butter or oil a 9"x13" baking dish and scoop the bread pudding mixture into it. Sprinkle with the reserved cheese and bake until crusty, golden brown and just set in the middle (about 45 minutes). Let stand for several minutes, cut into squares and serve.