Bring a large pot of salted water to a boil.
In a large, high-sided skillet, heat the oil over medium-high heat. Add the bacon and cook, stirring occasionally, until crispy around the edges, about 5 minutes. Carefully drain off all but 3 tablespoons of the fat, reserving the excess for later use.
Reduce the heat to medium and stir in the red pepper flakes, oregano, and garlic. Cook, stirring constantly, until fragrant, just a few seconds. Add the onion, generously season with salt and pepper, and cook, stirring, until the onion becomes translucent, about 5 minutes. If the pan becomes dry, add more reserved bacon fat. Stir in the tomato paste, cooking for about 3 minutes until it deepens in color. Turn off the heat and stir in the vodka. Add the pasta to the boiling water and cook according to the package instructions until 2 minutes shy of al dente.
While the pasta cooks, turn the heat under the sauce to high and cook, stirring constantly, until the vodka reduces by three-quarters, about 2 minutes. Add the cream and bring to a simmer, then remove from heat.
Reserve 2 cups of pasta water, then drain the pasta. Add the pasta to the skillet with the sauce, along with 1 cup of pasta water and most of the pecorino. Cook over medium-high heat, stirring vigorously, for 5 to 7 minutes until the sauce clings glossily to the noodles. Add more pasta water if the sauce appears dry. Remove the garlic cloves. Taste and adjust seasoning with additional salt and pepper, if needed.
Divide the pasta among plates, sprinkling with the remaining pecorino. Add three spoonfuls of ricotta to each serving and garnish with fresh parsley to balance the richness.