In a large skillet, melt the 2 tablespoons butter over medium-high heat. Add the garlic and saute for about 30 seconds, just enough to make the garlic sizzle. Add the mushrooms and saute briefly.
Add the shrimp and saute for about 30 seconds, until the shrimp is just half cooked.
Add the wine and, using a wooden spoon, stir to loosen any brown bits on the bottom of the pan. Let cook for 2 minutes, stirring, to finish cooking the shrimp and reduce the liquid. Remove the shrimp to a warm plate and cover with foil.
Add the heavy cream to the pan and let cook for 3 minutes to reduce. Stir in the lemon juice. Remove the pan from the heat and add the 4 tablespoons cold butter, 1 tablespoon at a time, stirring in the next piece after the one before it has just melted.
Season with salt and white pepper and stir in the bread crumbs. Return the pan to the heat, add the spinach, and cook, stirring for 1 1/2 minutes or just until the spinach has wilted.
Return the shrimp to the pan and stir to coat and heat through.
To serve, divide the angel hair pasta between two warmed serving dishes. Arange the shrimp on top, spoon the remaining contents of the pan equally over the shrimp, and sprinkle with the toasted pine nuts.