Rutabaga Purée with Brown Butter & Mascarpone

Ingredients

• 4 tbsp unsalted butter
• 1 large shallot or 1 medium onion (, peeled & coarsely chopped)
• 1 large rutabaga ((about 2 pounds), peeled and coarsely chopped)
• 1 t coarse salt (, pluse more to taste)
• 1 c chicken stock
• 1 pinch freshly cracked black pepper (, to taste)
• 1 tsp fresh or dried thyme leaves
• 4 tbsp mascarpone cheese