Wash hands with soap and water.
Dry out the bread. Cube the slider rolls into 1-inch squares and lay out on a baking sheet in a single layer. Leave out at room temperature to dry overnight. OPTIONAL: You can skip this step by toasting the bread cubes at 350 °F in a preheated oven for 10 to 15 minutes or until the edges are crispy.
Grease a 9 x 13-inch baking dish and set aside.
Combine cubed bread, ham, pickled jalapenos, onions and cheese in a large bowl. Transfer to the prepared baking dish.
Combine eggs, milk, crema, salt and pepper in a separate large bowl. Mix until ingredients are evenly combined.
Pour egg mixture over bread mixture. Press down to submerge everything in the egg mixture.
Wash hands with soap and water after handling eggs.
Cover casserole with plastic wrap and refrigerate overnight or at least 2 hours.
Preheat oven to 375 °F.
Remove casserole from the refrigerator, and let it sit at room temperature while the oven is heating. Bake uncovered for 55 to 65 minutes until internal temperature reaches 160 °F on food thermometer
Cut into squares and serve immediately.