Preheat the oven to 375 and put racks at the upper middle and lower middle positions.
Line two sheet pans with aluminum foil.
Spiralize your zucchini into 1/8 to ¼ inch zoodles (3-5 mm), cutting them into 12 inch lengths with a kitchen shears.
Toss the zoodles with 1 Tbsp olive oil, ½ tsp salt, ¼ tsp pepper. Spread on to one of the sheet pans.
Toss the tomatoes, onion, garlic, 2 Tbsp of olive oil, tomato paste, oregano, pepper flakes, ½ tsp salt and ¼ tsp pepper together into a bowl. Spread the tomato mix onto the other sheet pan.
Roast both for about 25 minutes, with the tomatoes on the lower rack and the zucchini on the upper rack. Remove when the tomato skins start to pucker. Put the zucchini into a colander to drain any excess liquid.
While those are in the oven, bring the cream and butter to a simmer in a large saucepan over medium low heat. Reduce the heat to low and simmer for 10-15 minutes. Stir in the Parmesan, ½ tsp salt and ¼ tsp pepper and simmer until the cheese is melted.
Add the zucchini to the cream sauce and gently toss them together. Transfer to a serving platter and top with the roasted tomatoes. Season with salt & pepper and garnish with the basil.