Preheat oven to 375 degrees F (190 degrees C). Spread pine nuts, hazelnuts, almonds, cashews, and walnuts onto a baking sheet.
Bake in the preheated oven, stirring occasionally, until nuts are roasted and fragrant, 5 to 10 minutes. Remove nuts from oven and cool slightly. Crush nuts using a rolling pin.
Boil chestnuts in a pot of water until tender, about 10 minutes. Drain and finely chop.
Heat olive oil in a large skillet over medium-high heat; saute onions and garlic until onions are tender and garlic is lightly browned, about 5 minutes. Remove garlic and stir parsley, salt, and pepper into onion; add mushrooms. Reduce heat to low and continue cooking until mushrooms are softened, 5 to 10 minutes. Remove skillet from heat.
Heat butter in a separate large skillet over medium-high heat; saute rice until toasted and fragrant, about 2 minutes. Stir wine and vegetable stock, 1 cup at a time, into rice, allowing stock to evaporate before each addition until rice is tender and all the liquid has been absorbed, 15 to 20 minutes.
Stir mushroom mixture, roasted nuts, and boiled chestnuts into rice mixture and remove from heat.