Preheat oven to 375°F (190°C). Line a baking sheet with foil and parchment paper.
In a large bowl, combine ground beef with dried onion, garlic, crushed fennel, salt, and pepper. Mix gently with your hands.
Divide the mixture into 8 equal portions and shape into patties. Press a slight indentation in the center of each.
Place patties on the prepared sheet pan and bake for 20 minutes or until internal temp reaches 160°F.
Add cheese slices during the last minute of baking and let them melt.
Toast hamburger buns under the broiler or wrap them in foil and warm in the oven.
Assemble burgers with your favorite toppings and sauces.