Preheat the oven to 450°F (232°C). Drizzle the olive oil in a 9-by-13-inch baking dish and use your hand to slick the entire surface.
In a large bowl, combine the ground beef, ricotta, eggs, bread crumbs, parsley, oregano, salt, fennel, and red pepper flakes. Gently mix by hand until everything is thoroughly incorporated.
Roll the mixture into round, golf ball-size meatballs (about 1 1/2 inches in diameter), making sure to pack the meat firmly. Place the balls in the prepared baking dish, being careful to line them up snugly in even rows vertically and horizontally to form a grid. The meatballs should be touching one another.
Roast until the meatballs are firm and cooked through and a meat thermometer inserted into the center of a meatball reads 165°F (74°C), 20 to 30 minutes.
While the meatballs are roasting, warm the tomato sauce in a small saucepan over medium-high heat, stirring often.
When the meatballs are firm and fully cooked, remove them from the oven and tip the pan to remove the excess grease into the garbage. Pour the tomato sauce over the meatballs and turn to coat. Return the meatballs to the oven and continue roasting for another 15 minutes.
Serve as desired. Originally published October 28, 2013.