Peel, core, and chop apples; toss in bowl with lemon juice. In separate bowl, combine brown sugar, cinnamon and nutmeg; stir into apples and set aside. In another bowl, combine flour, sugar and oats. Cut butter into flour until crumbly. Stir in nuts. Butter a 10×10″ dish and spread apples in bottom, then sprinkle with crumbs. Bake 375°F for 30-45 minutes till browned. Serve warm.