In a frying pan over medium-high heat, melt butter and cook zucchini, garlic and onions for 2 to 3 minutes. Remove from heat, add basil and cayenne, and salt and pepper generously.
Top each bread slice with about 1 tbsp (15 ml) of zucchini mixture. Cover with cheese and broil until golden.
Serve hot or cold with aperitifs or with a salad as a first course.
Tips: Make bigger Zucchini Bruschetta with Canadian Swiss Cheese to serve 4 to 6 people by using a crusty loaf of Italian or French-style bread about 4 inches (10 cm) wide.