Put the flour on a plate and season with a healthy amount of salt and pepper; mix with a fork to combine evenly. Dredge the shrimp in the seasoned flour to coat all sides.
Heat the butter and oil in a heavy bottomed pan over medium heat until butter stops foaming and just starts to turn a light brown. Add the shrimp, and give it a toss, saute for 5 minutes until the shrimp is firm and there is a crispy coating on the outside. Remove the shrimp to a side plate and cover to keep warm.
Put the pan back on the heat and add the garlic and shallots. Cook and stir for 1 minute until soft. Add the lemon juice and chicken broth, give it a stir and let it cook down for 1 minute to thicken slightly. Put the shrimp back in the pan and coat in the lemon sauce. Season with salt and pepper and garnish with chopped parsley before serving.