How to Make It
Preheat oven to 350°F. Bring half-and-half, jalapeños, and garlic to a simmer in a medium saucepan over low. Remove from heat, and let steep 15 minutes. Strain jalapeño cream through a fine mesh strainer into a medium bowl, pressing down on jalapeños and garlic; discard solids.
While jalapeño cream steeps, place potatoes in a large pot, and add cold water to cover by 1 inch; lightly salt. Bring to a boil over high. Reduce heat to medium, and simmer, uncovered, until potatoes are fork-tender, 10 to 12 minutes. Drain well in a colander. While still very hot, pass potatoes through a ricer into pot (a potato masher or food mill will also work). Fold in jalapeño cream, sour cream, softened butter, and 3/4 teaspoon of the salt until blended. Stir in Cheddar, pepper Jack, and 1 cup of the cooked bacon. Spoon potato mixture into a lightly greased 13- x 9-inch baking dish.
Toss together crackers, melted butter, and remaining 1/8 teaspoon salt in a medium bowl; sprinkle over top of potatoes. Bake in preheated oven until heated through and top is golden brown, about 20 minutes. Sprinkle with remaining 1/2 cup bacon.
Though even the more heat sensitive palettes in our test kitchen did not find this mashed potato bake to be overtly spicy, if you are at all concerned about the heat level, feel free to lose one jalapeño from the recipe.