For the toast: Heat the oven to 400 degrees F. Brush the bread slices on both sides lightly with olive oil and put them on a baking sheet. Toast until lightly golden, 3 to 5 minutes, depending on how crunchy you like them. Turn and toast the other side.
For the sauteed mushrooms with creme fraiche and parsley: Melt the butter in a medium saute pan until it foams. Add the mushrooms and cook until they soften. Add the garlic and saute for another minute. Season with salt and pepper. Deglaze with white wine, bringing it to a boil and reduce until syrupy. Stir in the creme fraiche. Scatter over some parsley and add a squirt of lemon juice. Spoon the mushroom mixture on 8 pieces of toast.
For the black olive tapenade with tomato and basil: Toss the tomato with the oil and basil, season with salt and pepper. Spread 8 pieces of toast with the tapenade and top with the tomato mixture.
For the crushed fava beans with mint and chevre: Bring a pot of water to a boil and salt it, as for pasta. Blanch the fava beans for 1 minute, to loosen their skins. Drain and run under icecold water. Remove the skins and discard, keeping only the soft, bright, jade-green insides. Place in a bowl and mash with a drizzle of oil, season with salt and pepper. Stir in the mint. Spread 8 pieces of toast with the chevre and top with the fava puree.