Boil water for pasta; have it ready.
Heat olive oil and melt butter in large skillet over medium heat. Add onions and garlic and cook for two or three minutes, or until onions are translucent. Add shrimp, then stir and cook for a couple of minutes. Squeeze in lemon juice. Add wine, butter, salt and pepper, and hot sauce. Stir and reduce heat to low.
Throw angel hair pasta into the boiling water. Cook until just done/al dente. Drain, reserving a cup or two of the pasta water.
Remove skillet from heat. Add pasta and toss, adding a splash of pasta water if it needs to be thinned. Taste for seasonings, adding salt and pepper if needed.
Top with grated Parmesan and minced parsley and serve immediately.