1. Preheat the oven to 375°F (190°C).

2. Cook the penne according to the package instructions until al dente. Drain and set aside.

3. In a large skillet, melt the butter over medium heat. Add the canned chopped tomatoes, green beans, and black beans. Cook for 5 minutes, stirring occasionally.

4. Add the allspice and accent seasoning to the skillet. Stir well to combine.

5. In a small bowl, mix together the gluten-free flour and baking powder. Add this mixture to the skillet and stir until well combined.

6. Gradually pour in the boiling water while stirring continuously. Cook for an additional 2 minutes until the sauce thickens.

7. Remove the skillet from heat. Add in the cooked penne and mix well.

8. Transfer the mixture to a baking dish and sprinkle with reduced fat shredded cheddar cheese.

9. Bake in the preheated oven for 20-25 minutes or until the cheese is melted and bubbly.

10. Serve hot and enjoy!