Preheat oven to 350 degrees F.

Heat large covered saucepot of salted water to boiling on high. Cook spaghetti as label directs.

Meanwhile, in 12-inch skillet, cook bacon on medium 6 to 8 minutes or until crisp, stirring occasionally. With slotted spoon, transfer bacon to paper towels to drain. To fat in pan, add onion. Cook 4 minutes or until tender, stirring occasionally.

While onion cooks, in very large bowl, whisk ricotta, eggs, milk, cayenne, half of Parmesan, and 1/4 teaspoon salt.

Drain spaghetti well. Stir into ricotta mixture along with peas, bacon, and onion. Spread in even layer in 3-quart shallow baking dish. Sprinkle remaining Parmesan on top.

Bake 30 to 35 minutes or until set.