Dice the tomatoes (halved if using grape tomatoes), keeping the seeds. Set aside.
Dice the avocado, in the shell, if possible. Here’s how: Cut the avocado in half by scoring the shell top to bottom, all the way around. Be careful not to cut yourself. If you are unsure, dice the avocado the way you normally would and ignore these instructions.
After scoring, gently pull the halves apart. Remove the pit.
Using one of the halves, and without cutting the shell, gently make slices from top to bottom.
With the same half, and without cutting the shell, gently cross-cut the slices from left to right to dice the avocado. Leave the diced avocado in the shell.
Repeat steps four and five with the second half of the avocado. Set the avocado aside.
In the glass casserole pan, add the refried pinto beans, spreading the layer out evenly across the bottom.
Using about half of the tomatoes, add a layer on top of the refried pinto beans.
Using half an avocado, add a layer of diced avocado on top of the tomatoes.
On top of the avocado, add the refried black beans. Spread the layer out evenly across the pan.
Add the cheese as a layer on top of the refried black beans. If you are using a long casserole pan, use the whole bag of cheese.
Add the remaining half of the tomatoes on top of the cheese
Add the remaining avocado on top of the tomatoes.
Serve immediately.