For the veggies: Place a large skillet over medium-high heat. Add the oil and heat until shimmering. Carefully place the squash and tomatoes in the skillet. Sprinkle with 1/4 teaspoon salt and 1/4 teaspoon pepper. Cook without stirring until squash is golden brown on both sides, about 2 minutes per side, and tomato skins begin to blister and crack. Remove the vegetables from the skillet and set aside. Add the greens and vegetable stock to the pan. Cook, stirring occasionally, until the greens have wilted and the liquid is reduced by half, about 5 minutes. Add the cream and cheese. Stir until the cheese melts and the cream thickens, about 3 minutes. Stir in the squash and tomatoes and cook for 1 minute more to warm through. Remove from heat.
For the topping: Place a small nonstick pan over medium high heat. Add the oil and heat until shimmering. Sprinkle the crackers into the oil in an even layer. Cook until browned, 1 to 2 minutes. Remove from the heat and stir in the onions and parsley. Sprinkle over the creamed veggies when ready to serve.