Makes 4 sandwiches
2 tablespoons extra-virgin olive oil
2 tablespoons thinly sliced shallot
2 (8 ounce) packages cremini mushrooms, thinly sliced
1 teaspoon chopped fresh thyme
1 (5 ounce) package baby spinach
2 tablespoons balsamic vinegar
8 (1/2-inch) slices whole-grain bread
2 tablespoons unsalted butter, softened
4 slices provolone cheese
½ cup shredded fontina cheese
Heat oil in a large nonstick skillet over medium-high heat. Add shallot; cook, stirring often, until softened, about 3 minutes. Add mushrooms and thyme; cook, stirring occasionally, until the mushrooms soften and turn golden brown, 8 to 10 minutes. Add spinach and vinegar; cook, stirring constantly, until the spinach is wilted and the vinegar is mostly evaporated, about 2 minutes. Transfer the mixture to a medium bowl.
Coat 1 side of each bread slice evenly with a thin layer of butter. Flip 4 slices butter-sides down; top each with 1 slice provolone, 1/3 cup mushroom-spinach mixture and 2 tablespoons fontina. Top with the remaining bread slices, butter-sides up. Cook until crispy and browned on the bottom, 2 to 3 minutes. Carefully turn the sandwiches over and continue cooking until the cheese has completely melted, about 2 minutes.
385 Calories