Preparation

• Position a rack in the center of the oven and heat to 350°F. Butter a rectangular ovenproof baking dish large enough to hold the celery hearts in one layer.
• Trim a sliver off the bottom of each celery heart, taking care to leave them intact. Use a vegetable peeler to remove any tough stringy parts of the outer ribs of each heart. cut 1 inch off the top of each heart. Chop this part (you should have about 1/2 cup), and set aside. Slice each heart in quarters lengthwise.
• In a large skillet, heat the 1 Tbs. butter and the oil over medium heat. In batches, cook the celery hearts, adjusting the heat as necessary and turning as one side browns, until lightly browned all over, 11 to 12 minutes total. Transfer the celery hearts to the prepared baking dish.
• Return the skillet to medium heat and add the pancetta. Cook, stirring occasionally, until beginning to brown, about 5 minutes. If the skillet looks dry, add a drizzle of oil. add the carrot, onion, garlic, and reserved  chopped celery. Season with 1/4 tsp. salt and a light grind of pepper. Cook, stirring occasionally, until the vegetables have begun to soften, about 5 minutes. Raise the heat to medium high and pour in the wine. Cook, stirring, until the wine has mostly evaporated, about 30 seconds. Add the tomatoes and cook, stirring occasionally, for 2 to 3 minutes. Remove from the heat.
• Scrape the vegetables over the celery hearts and sprinkle the Parmigiano on top. Cover with foil, and bake for 1 hour. Uncover and bake until the celery is tender and the cheese on top is nicely browned, another 20 to 25 minutes. Serve hot or warm, garnished with parsley, if you like.