Heat oven to 350°F (176°C). Spray an 20 centimeter square baking dish with cooking spray and set aside.
Melt one tablespoon (15 grams) butter over medium heat in a large non-stick skillet. Add panko and toast until golden brown, stirring occasionally, about two to three minutes. Remove to a bowl and set aside.
Heat oil in the same skillet over medium heat. Add mushrooms, 1/2 teaspoon (three grams) salt and 1/4 teaspoon (one gram) pepper. Cook until mushrooms have softened and begun to brown, about five to seven minutes. Add garlic and cook for two minutes. Add spinach and cook until wilted, about two minutes. Remove to a bowl and set aside.
Melt the remaining three tablespoons (45 grams) of butter in the same skillet over medium heat. Add flour and cook, stirring constantly, for one minute. Stir in paprika and the remaining 1/2 teaspoon (three grams) of salt and 1/4 teaspoon of pepper. Whisking constantly, add cream and cook until bubbling and thickened, about three minutes. Stir in goat cheese until melted. Remove from heat.
Combine cooked pasta and wilted spinach with goat cheese mixture, tossing to combine. Spoon mac & cheese into prepared dish and sprinkle with panko crumbs. Cover with tinfoil and bake until heated through, about 20 minutes. Drizzle with truffle oil just before serving.