Boil 12 ounces each green beans and yellow wax beans until tender, 5 to 7 minutes; drain. Toast 1/2 cup chopped walnuts with 1/2 teaspoon each kosher salt, pepper and sugar in a skillet with olive oil,5 minutes; remove to a bowl. Add 2 tablespoons oil, 3 sliced garlic cloves and 2 teaspoons chopped marjoram to the skillet. Cook, stirring, until softened, 1 minute. Stir in the beans, season with salt and pepper and top with the walnuts.