Slice tomatoes in half, then place on a large baking sheet. Brush each one with olive oil, then sprinkle with salt. Roast for 30 minutes, until the tomatoes are wilted and soft. Remove from heat and allow to cool.
In a large pan over medium heat, sauté the onions in a splash of olive oil until translucent, about 5 minutes. Add in the garlic and cook for another 1-2 minutes.
Sprinkle the flour over the onions & garlic and stir everything together. The flour should form a pasted coating on the onions. Cook for 1 minute, then whisk in the white wine, milk, cream, and salt. Whisk any flour beads until they no longer remain and the sauce is thick and velvety. Turn heat to low and continue to cook, uncovered, for 15 minutes, stirring occasionally.
Meanwhile, boil the pasta and cook to al dente. Strain the cooked pasta and place back into its pot and drizzle with ~1 tablespoon of oil. This will keep the pasta from sticking to itself.
Once the cream sauce has thickened, pour it into a large blender and toss in the Campari tomatoes. Blend on high speed for 3 minutes, then strain the sauce over a fine mesh sieve to remove any remaining pieces of tomato.
Pour the strained sauce over the pasta and stir to combine. Top with the Kumato & Y.E.L.O. tomatoes, then garnish with a healthy dose of parmesan!