Heat 2 tbsp of water in a large pot over medium-high heat. Saute the onions until translucent for about 5 minutes. Add the garlic and bell peppers and continue to saute for another 5 minutes.
Reduce the heat to medium and add all of the other ingredients except 1/2 cup of cheese to the pot and mix well. Cook until the vegetables, tempeh crumbles, and "cheese" are heated through.
Spoon Mexican Mac and Cheese into a oven safe dish lined with parchment. Sprinkle the top with the 1/2 cup of "cheese" and place in the oven for 5 to 6 minutes to add a nice "cheesy" crust.
Notes
A topping suggestion would be a spattering of Sriracha sauce which will make for a caliente addition. Be careful of the sodium amount, balance with other recipes that have lower sodium values.