Preheat an indoor grill or barbecue to medium-high. Cut the bread widthwise in half. Now cut each half piece of bread lengthwise in half. Grill the bread, on the cut side, until nicely coloured, about 30 seconds. Set bread, cut side up, on a nonstick baking sheet. Trim a little from the stem end of each mushroom, and then cut each mushroom into 1/2” slices. Brush the mushroom slices lightly with olive oil. Grill 1 to 2 minutes on each side, until nicely coloured and just tender. Set mushrooms on a plate.
Set and oven rack 6” below your oven’s broiler. Preheat the broiler to high. Spread each piece of bread with pesto and mayonnaise. Top each piece of bread with 2 halves of havarti cheese. Divide and top the cheese with the tomato and mushrooms. Broil the sandwiches 2 to 3 minutes, or until the cheese just begins to melt. Set the sandwiches on plates. Drizzle with a little balsamic vinegar and olive oil. Sprinkle with salt, pepper and parsley and serve.
This recipe will serve two if enjoyed on its own. It will serve four and make a light meal if served with a side salad.
Note: Piccolo ciabattini is Italian-style bread about half the size of a baguette. It is available in our bakery section. Sliced havarti cheese is available in our deli department.