Finely chop all the bell peppers and purple cabbage.
Combine the rice with the vegetables in a slow cooker, and pour 1 3/4 cup chicken broth over it. Set it on high for 2 1/2 hours, or low for about 4 hours. Make sure the rice has absorbed all the liquid.
Unplug the slow cooker, and add milk, butter, and Monterrey cheese.
Stir to combine and let sit for 5 minutes. Season with salt if desired.