Bring a large pot of salted water to a boil and cook the whole grain linguine according to package instructions until al dente.
While the pasta cooks, heat the olive oil and ghee in a large skillet over medium heat.
Add the minced garlic and red pepper flakes to the skillet, sautéing for about 1 minute until the garlic is aromatic but not browned.
Increase the heat slightly and add the shrimp to the skillet in a single layer, seasoning with sea salt and black pepper.
Cook the shrimp for 2 minutes per side until they are pink, opaque, and cooked through.
Stir in the baby spinach and cook for 1 minute until the leaves are just wilted.
Drain the pasta, reserving a splash of pasta water, and add the noodles directly into the skillet with the shrimp.
Add the lemon juice, lemon zest, and fresh parsley, tossing everything together to coat the pasta in the garlic sauce.
Serve immediately, adding a spoonful of reserved pasta water if needed to loosen the sauce.