Crumble ricotta in a bowl along with lemon zest and a little salt and pepper. Set aside.
Melt butter in frying pan, along with oil to prevent the butter from burning.
Add the garlic to pan and stir for 1 min, or until fragrant. Add the mushrooms and thyme leaves stir until soft and tender. Add lemon juice, salt and pepper and stir to combine.
Place some ricotta onto the slices of bread, top with the mushroom mixture and serve.