Preheat oven to 400. Line a rimmed baking sheet with parchment paper or foil.
Toss beans with oil, nuts, salt and pepper.
Spread your bean mixture on the baking sheet and roast until the beans are tender, about 12 minutes, tossing once halfway through baking.
Serve immediately with whatever you are making for dinner!
Notes
Green beans: You are looking for the fresh ones in your produce section, and most supermarkets will have them already trimmed and ready for you! If not, just snap off the end bit with the stem on it.
Walnuts: Look for shelled walnuts in the baking aisle. And you can swap out the walnuts for cashews or pecans or (swoon!) macadamia nuts if you like.