Fill a large pot with lightly salted water and bring to a rolling boil. Cook fettuccine at a boil until tender yet firm to the bite, about 8 minutes. Drain; reserving about 1/2 cup pasta water.

Meanwhile, heat butter and olive oil in a large skillet over medium heat until butter is melted. Slice 2 garlic cloves, add to the skillet, and cook until lightly browned, about 2 minutes. Remove garlic from the skillet and discard.

Carefully add shrimp to the skillet with a pinch of salt and pepper. Cook until shrimp is pink, opaque, and curled into a “C” shape, 2 to 3 minutes per side. Remove from the skillet and keep warm.

Add shallot to the skillet and cook, stirring, until softened, 2 to 3 minutes; stir in red pepper flakes. Mince remaining 2 garlic cloves; add to skillet and cook, stirring, until fragrant, about 30 seconds.

Add sliced tomatoes, minced parsley, and white wine. Bring to a boil, and cook for 2 to 3 minutes. Stir in chopped spinach; cook until just wilted and bright green. Return cooked shrimp to the skillet; stir in cream. Season to taste with salt and pepper.