Combine cream cheese, sour cream, mayo, salt and pepper in a mixing bowl and beat it with an electric mixer until smooth.
Fold in grated Fontina cheese and Mozzarella cheese, set aside.
Thinly slice mushrooms. Drain artichoke hearts and chop them into smaller pieces.
Preheat a cooking pan over medium heat and add oil. Saute mushrooms and artichokes until mushrooms are softened. Smash garlic and add it to the pan. Cook until mushrooms are done. Add mushroom mixture to the bowl and mix until fully incorporated.
Preheat the oven to 350.
Carefully cut off the top of the bread. Scoop out insides of the bread but make sure not to make the crust too thin or make any holes.
Transfer the dip mixture into the bread bowl, place bread top back on and put filled bread onto a baking sheet.