Preheat the oven to 400° F. Line a rimmed baking sheet with foil and place the bacon strips on the foil, without overlapping. Cook for 15 minutes, flip and cook 5-7 minutes until crispy. Dice and set aside.
Cook the pasta according to box instructions. Reserve 1/2 cup of pasta water when finished cooking.
Meanwhile, heat 1 tbsp of olive oil in a 12 inch skillet over medium heat. Add the garlic and shallot, and sauté for 1-2 minutes until fragrant. Whisk in the flour, then remove the pan from the heat and slowly whisk in the half and half. Reduce the heat to medium-low and return the pan to the burner. Whisk in the pumpkin, ricotta, sage, lemon juice, cinnamon, red pepper flakes, nutmeg, salt, and pepper. Thin the sauce with a little bit of the pasta water if needed and continue whisking until you have a smooth creamy sauce. (I used about 1/4 cup of pasta water in mine.)
When the pasta is finished cooking, drain and add it to the to the skillet with the sauce. Mix in the bacon, then divide between bowls and serve. Garnish with more fresh sage and pecorino romano cheese if desired.