Preheat the oven to 350 degrees F. Melt the butter in a large ovenproof skillet over medium-high heat. Add the tomatoes and cook until softened, 2 to 3 minutes. Add the lentils, curry sauce, 1/2 cup water and 1/4 teaspoon salt; stir well to coat. Bring to a simmer and cook, stirring occasionally, until the lentils are tender, about 8 minutes. Gradually add the spinach, stirring until wilted.
Reduce the heat to medium. Make 4 wells in the lentil mixture and crack an egg into each; spoon the heavy cream over the eggs. Continue cooking until the whites begin to set, 3 to 4 minutes.
Transfer the skillet to the oven and bake until the egg whites are just set but the yolks are still runny, about 10 minutes. (The eggs will continue cooking after you remove them from the oven.) Let rest, 5 minutes.
Meanwhile, wrap the naan in foil and warm in the oven, about 5 minutes. Cut into wedges and serve with the eggs. Photograph by Ryan Dausch