Cook the pasta according to package directions, drain, and transfer to a large bowl.
Meanwhile, heat the oli in a large skillet over medium heat. Add the shallots and cook, stirring until tender, about 5 minutes.
Stir in the thyme, salt, and pepper until well combined and thyme is fragrant. Add this mixture to the pasta and combine.
Heat the milk in a large skillet over medium heat. When tiny bubbles appear around the edges of the pan, reduce the heat to low and stir in the sour cream, and blue cheese. Stir until the cheese melts. Add the peas and stir until heated through, about two minutes.
Remove from heat and stir in the walnuts and parsley.