Place ½ cup butter in a small saucepan over medium heat. Cook, swirling occasionally, until the butter melts, foams, and develops golden-brown specks and a nutty aroma, about 5 to 7 minutes. Remove from the heat and let cool slightly.

Preheat the oven to 350°F. Lightly grease a 9-inch springform pan. Line the bottom with parchment paper and lightly grease the parchment with nonstick spray.

Cut the pears in half lengthwise, remove the cores, and slice into approximately ¼-inch-thick slices.

Arrange the pear slices in an overlapping pattern over the bottom of the prepared pan. Scatter the cranberries evenly over the pears.

In a small bowl, stir together the brown sugar, 2 tablespoons melted butter, maple syrup, cinnamon, and salt. Drizzle evenly over the fruit.

In a medium bowl, whisk together the gluten-free flour, baking powder, salt, and cinnamon.

In a large bowl, whisk together the brown sugar, granulated sugar, eggs, sour cream, vanilla, and orange zest until smooth. Slowly whisk in the cooled brown butter.

Add the dry ingredients to the wet ingredients and stir just until combined.

Carefully spoon the batter over the fruit and spread into an even layer. Bake for 40 to 48 minutes, or until golden and a toothpick inserted into the center comes out clean or with a few moist crumbs.

Let the cake cool in the pan for 10 minutes. Run a thin knife around the edge to loosen the cake.

Place a serving plate upside down over the cake pan. Carefully flip the pan and plate together. Lift away the pan and gently remove the parchment.

Serve warm or at room temperature with lightly sweetened whipped cream or vanilla ice cream, if desired.