Preheat the oven to 350°F. Set the oven to 350°F. Pour both cans of peaches and every drop of syrup into the 13×9 dish. Spend 2 to 3 minutes nudging the slices into one loose layer. Use the back of a spoon and keep several pieces overlapping naturally. Easy Peach Dump Cake with Canned Peaches (3 Ingredients) needs that syrup to hydrate the dry mix later. Then check the fruit layer from edge to edge. You should see glossy orange slices with shallow amber syrup pooling between them. If one corner looks dry, slide two or three slices toward it. Leave the peaches uncovered for no longer than 10 minutes. Wait longer and the syrup can settle unevenly. Even fruit coverage prevents dry pockets in the crust.

Keep the oven at 350°F. Sprinkle the full 15.25-ounce box of yellow cake mix over the peaches for 2 minutes. Move your hand from left to right in short passes. Then use your fingertips to break any large lumps. Don’t stir. The dry mix should form an uneven blanket while narrow peachy gaps remain visible near the edges. Next look for pale yellow coverage across the whole dish. Small ridges and shallow valleys are good. A thick mound in one corner will stay powdery after 45 minutes, so redistribute it now. Don’t press the mix into the syrup because that makes a gummy layer. A loose dry layer absorbs steam without turning pasty.

Keep the oven at 350°F. Cut 1 cup of cold salted butter into about 32 thin slices over 3 to 4 minutes. Place them across the cake mix with small uneven gaps. Start at the corners and work toward the center. Don’t stack the slices. Each piece should sit flat so the melting butter can travel across the powder. You should see pale butter covering roughly 80 percent of the surface. A few yellow cake-mix patches can remain between slices. But gaps wider than 1 inch may stay floury after baking. (My first pan had bare corners, and those spots never browned. Thin slices fixed it.) Broad butter coverage creates the crisp top.

Bake the dish at 350°F for 45 to 50 minutes on the center rack. At minute 30, rotate it 180 degrees without shaking. Then leave it undisturbed. Easy Peach Dump Cake with Canned Peaches (3 Ingredients) is ready when the center reaches at least 190°F and the top shows deep golden ridges instead of pale powder. Meanwhile watch the edges. The peach syrup should bubble steadily and the butter should stop forming clear puddles. You’ll smell toasted vanilla cake near minute 42. Pull the pan before the highest peaks turn dark brown. Go past 55 minutes and the syrup can scorch against the dish. Steady heat sets the crust before the fruit dries.

Remove the cake from the 350°F oven and rest it uncovered for exactly 15 minutes. Then cut or scoop one generous portion onto a white dessert plate. Slide under the crust first and lift slowly. Keep peach slices beneath the crumb topping. The portion should hold loosely while warm syrup settles around the lower edge. Finally look for a crisp golden top and a soft peach center. Steam should slow after 15 minutes and the syrup should thicken from runny to glossy. Serve sooner and the portion collapses into a puddle. Wait over 45 minutes and the crust loses some warmth. Resting lets the starches thicken the peach syrup.