Grease a 9x13-inch baking dish with butter or cooking spray. Line with parchment paper if desired for easier removal.

In a large mixing bowl, whisk together flour, granulated sugar, baking powder, baking soda, and salt. In a separate bowl, whisk buttermilk, eggs, melted butter, and vanilla until smooth. Pour wet ingredients into dry and stir gently until just combined.

In a small bowl, combine melted butter, brown sugar, cinnamon, and nutmeg to form a thick paste. Set aside.

Beat softened cream cheese with sugar, vanilla, and egg until completely smooth, about 2-3 minutes.

Pour half the pancake batter into prepared dish. Drop spoonfuls of cream cheese mixture over batter and swirl with a knife. Drizzle half the cinnamon mixture in ribbons and swirl. Add remaining pancake batter, more cream cheese dollops with swirls, then remaining cinnamon mixture to create a marbled top.

Cover tightly with plastic wrap or foil and refrigerate for at least 8 hours or overnight.

Preheat oven to 350°F (175°C). Remove baking dish from refrigerator and let sit at room temperature for 10-15 minutes while oven preheats.

Bake uncovered for 45-50 minutes until top is golden brown and center is set with slight jiggle. A toothpick should come out with just moist crumbs.

Cool for 10-15 minutes before slicing into squares. Serve warm with maple syrup, powdered sugar, fresh berries, or whipped cream.