Preheat oven to 350° F degrees. Make 1-inch diagonal cuts through the bread with a bread knife. Create a crosshatch pattern on the bread. Leave bottom of the bread intact, cuts should go ¾ of the way inside the bread. Drip pesto in the cuts with a spoon (or a squirt bottle). Place cheeses in between the slits as well.
Cover bread with aluminum foil on a baking sheet. Bake for 15 minutes then remove foil and bake for 5-10 minutes longer (until bread crust/ cheese is lightly golden brown). Let stand for a couple of minutes before serving.