1. Start by slicing the mushrooms you’ve chosen for the recipe.
2. Heat olive oil or butter in a frying pan over medium heat.
3. Add the sliced mushrooms to the pan and sauté them until golden brown and all moisture evaporates (about 5-15 minutes).
4. Add minced garlic to the pan with the mushrooms and sauté for an additional minute until fragrant.
5. Season the mushroom mixture with salt, pepper, and, if desired, a pinch of oregano, then taste and adjust the seasoning as needed.
6. Meanwhile, preheat your oven to 350°F (175°C).
7. Butter one side of each slice of rustic or French bread.
8. Place the buttered bread onto a baking sheet and toast in the oven until it turns lightly golden brown.
9. Remove the toasted bread from the oven and evenly spread the sautéed mushroom mixture across each slice.
10. Add a layer of shredded mozzarella or Swiss cheese over the mushroom mixture.
11. If desired, include fresh thyme leaves, whole grain Dijon mustard, or an herbed ricotta spread for extra flavor.
12. Place the prepared toasts back into the oven to bake until the cheese melts and becomes bubbly (around 2-10 minutes).
13. Alternatively, broil the toasts on high for 2-4 minutes, keeping a close watch to prevent burning.
14. Remove from the oven or broiler and serve immediately while warm and cheesy.
15. For storage, allow leftovers to cool completely, then refrigerate in an airtight container or freeze for extended storage.