Cook lentils in a medium pot of salted water until tender, 10–15 minutes; drain and let cool. Heat 1 Tbsp. oil in a medium skillet over medium-high heat. Add greens and cook, stirring occasionally, until wilted and bright green, about 3 minutes. Season with salt and pepper. Combine lentils, chickpeas, and remaining 2 Tbsp. olive oil in a medium bowl; season with salt and pepper. Divide among 2 bowls and top with greens, tomatoes, and Parmesan. Squeeze lemon over.