Before you start: Prepare and preheat: 25 minutes Bake: 22 minutes Cool base completely: 1 hour 30 minutes Frost and drizzle: 20 minutes Refrigerate to set: 1 hour Cut: 10 minutes Use the listed ingredient state: dry, cooked, thawed, drained or squeezed. Oven temperatures are for conventional ovens. Do not scale oven times in direct proportion to ingredients. Times are estimates; follow the doneness cues.
Equipment: 15-by-10-inch rimmed metal jelly-roll pan, at least 1 inch deep; parchment; mixer; rack; toothpick; dry microwave-safe bowl; knife
Recipe note: Refrigerate these cream-cheese-frosted bars promptly at 40°F or below; use within 3–4 days. Transport in an insulated cooler with ice packs. These are not shelf-stable mail gifts. Refrigerate perishable cooked dishes in shallow containers within 2 hours, or 1 hour above 90°F; keep the refrigerator at 40°F or below.
Treat cooling as a separate job
This is a cooled-and-chilled bar, not a tray to frost straight from the oven. Set up a rack and refrigerator space before mixing. Warm melted butter is suitable for the base; hot butter and a warm baked slab both create problems at later stages. Let the base become completely cool to the touch before the cream-cheese frosting goes on.
Keep the cranberries and white chocolate for the base separate from those reserved for the topping and drizzle. Small labeled bowls make those repeated ingredient names easier to follow.
Plan the triangle cuts before lifting
The written grid makes twelve rectangles, then twenty-four triangles. Mark three rows and four columns lightly before cutting all the way through the chilled slab. Use the parchment handles to lift it onto a stable board and support the base as it moves.
Wipe the knife between cuts so cranberry pieces and frosting do not drag across the next edge. Keep the bars refrigerated as the recipe requires. If only part of the tray is being served, return the remainder to cold storage instead of letting the whole slab wait out the gathering.
Timing and servings are estimates. Equipment, ingredients and portion sizes affect the result.