Crush the Ritz crackers. Some size variance is ok here. I like to smush them while they're still in their sleeves and then empty them into a bowl so as not to soil extra dishes.
Put the olive oil in a pan and cook at medium heat. Once hot, add the onions and sauté until translucent. This should take about 3-4 minutes. Mix the cooked onions into the crushed crackers.
Add the beaten eggs to the cracker mixture, followed by the rest of the ingredients. Then transfer to a greased muffin tin. Feel free to overstuff, as these won't really be rising, and the taller these are, the better they'll look. I liked the idea of going without muffin liners. Instead, I placed two strips of parchment paper in each cup in a plus sign formation. That way I could easily pop the stuffins out when they were done. If you want to use regular muffin liners, go for it.
Cover the muffin tins with foil and put them in the oven for 15 minutes. At the 15 minute mark, remove the foil and put them back in for another 5 minutes. Your stuffins should be golden and a little bit crisp!