Cook macaroni in a pot of generously salted boiling water until just al dente; it will finish cooking in the oven. Drain and toss with pulled pork and barbecue sauce; set aside.
Combine the cream, garlic, shallots, and thyme in a large saucepan over medium heat; bring to a simmer cook, stirring often, until reduces by ¼. Whisk in the cheddar, chile paste, and mayonnaise; taste, adding salt and pepper as desired.
Fold cheese mixture into macaroni and pork mixture, transfer to a shallow baking dish, and top with crumb topping; bake until golden and bubbly, about 40 minutes.
Serve at once.