Heat a large nonstick skillet over-medium low heat until hot. Add the oil, garlic and crushed red pepper. Cook, stirring, until fragrant, about 1 minute. Add the tomatoes and 1 cup of water. Simmer, stirring occasionally and gently smashing the tomatoes with a wooden spoon or silicone spatula, until some of the tomatoes start to burst, 10 to 15 minutes.
While the sauce cooks, prepare the zoodles: Spiralize the zucchini into fettuccine-shaped "noodles." Place in a medium bowl and set aside.
Once the sauce has cooked and some of the tomatoes have burst, add 1 more cup of water, the miso, salt and pepper. Stir together.
Add the zoodles and cook for 3 to 4 minutes then add the shrimp and cook, tossing occasionally, until the shrimp has cooked through and the zoodles are tender, 3 to 4 minutes. If the sauce looks too dry, stir in a little more water. Remove from the heat and stir in the sliced basil. Toss together.
Divide among 4 shallow bowls, garnish with basil leaves and serve.
If you don't have a spiralizer, use about 24 ounces store-bought zoodles (spiralized zucchini).