• Step 1
• Heat the stock in a saucepan to a simmer.
• In a large skillet, heat the butter and olive oil over medium heat. Once the butter has melted, add the shallot and sauté for 2-3 minutes, until softened and fragrant.
• Step 2
• Add the squash and cook, stirring occasionally, until softened, about 6-8 minutes. Add the arborio rice and sauté for another two minutes while stirring, then add the thyme. Pour in the wine and cook until it has been absorbed. Add the hot stock, a ladleful at a time, continuing to stir.
  
• Step 3
• While you continue to cook the risotto, make the garnish. Heat the butter in a small saucepan over medium-high heat, and add the sage when melted. Fry the sage until crispy, about 2-3 minutes, being careful not to burn it. Remove from heat.
  
• Step 4
• Continue to add stock to the rice, stirring constantly, until the rice is cooked. The rice should still be firm, and the risotto should be saucy and nearly run on a plate. Turn off the heat and stir in the Parmigiano-Reggiano and the mascarpone.
• Step 5
• Garnish each plate with the fried sage and drizzle with a little balsamic vinegar.
  

Options:

• You can use another winter squash in lieu of butternut—acorn squash, delicata squash, or whichever variety you like.