Farfalle with Arugula and White Beans

Ingredients

• coarse salt and freshly ground pepper
• 12 oz farfalle
• 4 tbsp unsalted butter ((1/2 stick), cut into pieces)
• 4 garlic cloves (thinly sliced)
• 1 lb baby arugula
• 1 can cannellini beans ((15 1/2 ounces), drained and rinsed)
• 1/3 cup walnut pieces (toasted, for garnish)