Traditionally called malaiwala, “the one with cream,” this casserole is a Punjabi twist on a ratatouille-style summer side. Make this a main dish by adding cubed paneer, a firm Indian cheese.
Preheat grill to high (450°F to 500°F). Toss together squash, canola oil, 2 teaspoons salt, and 1/2 teaspoon black pepper in a large bowl until evenly coated. Place squash in a single layer on oiled grates; grill, uncovered, until char marks form, about 4 minutes per side. Set aside.
Preheat oven to 400°F. Heat ghee in a 12-inch cast-iron skillet over high until shimmering. Add onions, and cook, stirring often, until translucent, about 10 minutes. Stir in ginger, cumin, and fenugreek seeds; cook, stirring often, 1 minute. Sprinkle with cayenne, 2 teaspoons salt, and remaining 1/4 teaspoon black pepper. Cook, stirring occasionally, 1 minute. Stir in tomato paste and garam masala; cook, stirring often, 1 minute. Stir in white wine, and cook until almost evaporated, about 30 seconds.
Remove from heat; stir in lemon juice, grilled squash, and remaining 1 1/2 teaspoons salt. Whisk together ricotta and cream in a medium bowl. Gently fold ricotta mixture into squash mixture.
Stir together Parmesan, panko, and butter with a fork in a medium bowl until crumbly. Sprinkle panko mixture over squash mixture in skillet.
Bake in preheated oven until filling is bubbly and topping is golden brown, about 20 minutes. Let stand 10 minutes before serving.
This dish can be made a day ahead and reheated in the oven or assembled the day before and baked just before serving.