Open-Faced Spinach Sandwiches
2 teaspoons olive oil (you can substitute a little bacon fat for some of the olive oil if you have it)
1/2 teaspoon brown mustard seeds
1/2 teaspoon cumin seeds
1 white or yellow onion, halved vertically, then thinly sliced
2 cloves of garlic, minced
1 package of button or cremini mushrooms, thinly sliced
red pepper flakes
salt and black pepper to taste
2 packages baby spinach
1/2 cup grated gruyere
1/4 cup grated parmesan
2 tablespoons butter
1 tablespoon flour
1/2 cup milk
1 oz. goat cheese
1/2 tablespoon spicy Dijon mustard
4 slices challah, lightly brushed with melted butter
Butter a small baking dish. (I used a 9-inch oval enameled cast iron dish, which was the perfect size.) Heat oven to 400 degrees.
Heat oil over medium-high heat in dutch oven. Add mustard seeds and cumin seeds, stirring until the seeds begin to pop. Add sliced onion and a pinch of salt. Cook until onions are soft. Add garlic and cook for about 30 seconds, until fragrant. Add mushrooms, red pepper flakes, and another pinch of salt. Cook, stirring occasionally, until mushrooms have released their water and are beginning to brown at the edges, about 10 minutes. Add spinach and cook, stirring occasionally, until spinach is wilted and most of the water has cooked out, about 10 minutes.
Put half of spinach mixture into baking dish. Top with gruyere and half of the parmesan, then top with other half of spinach mixture.
To make bechamel: Melt butter in small pot over medium heat. When bubbling has subsided, but before butter begins to brown, add flour and cook, whisking constantly for about a minute. Slowly add milk, whisking constantly until thickened, a few minutes. Remove from heat and add goat cheese and mustard, whisking until both are incorporated into the sauce. Pour bechamel over the spinach mixture, making sure to distribute it evenly. Top with remaining parmesan and bake until top is golden brown and bubbly, about 30 minutes.
During the last 5 minutes of baking, place buttered challah on baking sheet and toast in oven until lightly browned. Spoon spinach mixture over toasted challah and serve immediately.
