My loaf of artisanal bread was 1 inch thick and then 6 inches wide and by 12 inches long. When I sliced it and turned the slices on their sides, I had sort of cigar shaped slices that looked a bit like biscotti. Long, narrow slices. You can use whatever kind of bread you like. I just wanted to tell you what I was working with so you could visualize the size of mine and keep that in mind for proportions.
Take a pastry brush and coat one side of your bread slices with olive oil. This is one time when you are not going to skimp. Olive oil has some good health qualities, so go for it. Brush on a good layer and prepare to broil that one side of the bread by placing the slices on a cookie sheet, oil side up. Broil them just until the edges are slightly browned. Set aside.
Heat the butter and a few more teaspoons of oil in a sauté pan and put in your mushrooms and the Italian herbs. Sauté the mushrooms on Medium heat until they are browned on the edges. They should have given off much of their liquid. This will take about 8 to 10 minutes. They will shrink down to about 3 cups.
After you have drained your artichokes, put them in a food processor and chop them finely. If you don't have a processor, just put them on a cutting board and cut them up finely with a knife. You want to cut them finely so you don't have chunks. Dice them.
This can all be done a few hours ahead if you keep all ingredients covered and then begin to assemble later.
Take your bread pieces and spread a thin layer of artichokes on the broiled side. This doesn't take a lot. Artichokes go a long way in adding flavor. Then spread the mushrooms over the artichokes. They will also just cover the artichokes in a thin layer across the bread slices. If you are using a smaller round bread, you might end up with the bonus of mounded mushrooms on your bread slices. That's fine.
Heat the bruschetta at this point at 350 degrees for about 10 to 12 minutes to make sure they are nice and warm. Take your cheese slices and cut them in half. Put one-half slice on each piece of bruschetta. Put the bruschetta back in the oven for 5 minutes more to melt the cheese. Don't broil them. Baby Swiss cheese is so delicate, the broiler will disintegrate the cheese instead of just melt it. This is a kinder, gentler way to just lightly melt the cheese.