Cook nuts in oil in a 10-inch heavy skillet over medium heat, stirring, until golden, about 2 minutes. Transfer with a slotted spoon to towels to drain. Cook garlic, onion, pepper flakes, and 1/4 teaspoon salt and 1/4 teaspoon pepper in remaining oil, stirring occasionally, 8 to 10 minutes. Remove from heat.
Cook penne in boiling water until al dente. Reserve about 2 cups of pasta water, then drain pasta. Return pasta to empty pot; stir in cheese, butter, kale, onion mixture, 1 cup reserved pasta water, and salt and pepper to taste. Cook over low heat, stirring, 1 minute, moistening with additional pasta water if desired. Serve sprinkled with almonds and additional cheese.
Nutrition information per serving:
Calories520Fat24 gSodium700 mg
Carbohydrates64 gSaturated fat8 gCalcium230 mg
Protein18 gCholesterol27 mgDietary fiber9 g