Browned butter sweet potato filling swirled through a real maple cheesecake, all on a pre-baked gingersnap crust. Sixteen clean squares, made a day ahead.
Heat the oven to 350F. Line a 9x13-inch pan with parchment paper, leaving an inch of overhang on the long sides.
Pulse the gingersnaps to fine crumbs, then stir together with the melted butter and brown sugar until every crumb is damp.
Press the mixture into an even layer using the flat bottom of a measuring cup. Bake 8 to 10 minutes, until set and fragrant. Cool 15 minutes.
Make the Sweet Potato Filling
Melt the butter in a light-colored skillet over medium heat, swirling constantly. After 5 to 6 minutes it will foam, quiet down, and show brown flecks. Pour it into a bowl immediately, flecks included, and cool 10 minutes.
Whisk the cooled browned butter with the mashed sweet potato, brown sugar, egg, cinnamon, nutmeg, ginger, and vanilla until smooth. Set aside.
Make the Maple Cheesecake Layer
Beat the cream cheese and granulated sugar on medium speed for 2 full minutes, scraping the bowl twice, until completely smooth with no lumps.
Mix in the maple syrup, sour cream, and vanilla until glossy.
Add the eggs one at a time on low speed, stopping as soon as each one disappears into the batter. Do not overbeat.
Layer, Swirl, and Bake
Pour about three quarters of the cheesecake batter over the cooled crust and spread it level.
Dollop the sweet potato filling over the top in rows of tablespoon-sized spoonfuls, then dot the remaining cheesecake batter into the gaps.
Drag a butter knife in long parallel lines down the length of the pan, about halfway deep. Turn the pan a quarter turn and drag once more across the first lines. Stop after two passes.
Bake 45 to 50 minutes, until the edges are set and the center still wobbles slightly when nudged.
Turn the oven off, crack the door, and leave the pan inside for 30 minutes. Then cool completely on a rack.
Chill at least 4 hours or overnight. Lift out by the parchment and cut into 16 squares, wiping the knife clean between cuts.
Notes
Room temperature matters: let the cream cheese, eggs, and sour cream sit out for 1 hour before starting, or the cheesecake layer will stay lumpy.
Cool the sweet potato: warm puree loosens the batter and the swirl bleeds instead of holding its shape.
Canned puree works: use plain canned sweet potato puree, not candied yams in syrup, and blot it if it looks watery.
Real maple only: maple extract gives a candy note and none of the caramel depth the recipe is balanced around.
Storage: airtight in the fridge up to 5 days, or wrapped individually in the freezer up to 2 months.