Preheat the oven to 350°F. Generously grease a 10–12 cup Bundt pan with baking spray containing flour, making sure to coat all the grooves and crevices.

Add the butter to a light-colored saucepan over medium heat. Cook, stirring or swirling occasionally, until the butter melts, foams, and develops golden-brown milk solids with a rich, nutty aroma.

Immediately remove from the heat and transfer the browned butter, including the toasted milk solids, to a heatproof bowl. Allow to cool until warm ,but no longer hot.

In a large mixing bowl, combine the cooled brown butter, granulated sugar, and brown sugar. Beat for approximately 2 minutes until well combined.

Add the eggs one at a time, mixing well after each addition. Add the vanilla bean paste and mix until incorporated.

In a separate bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg or pumpkin pie spice, and kosher salt.

In another bowl, whisk together the whole milk and sour cream until smooth.

Add approximately one-third of the dry ingredients to the butter mixture and mix on low speed until just combined. Then add half of the milk mixture and mix briefly. Continue alternating the dry ingredients and milk mixture, beginning and ending with the dry ingredients. Mix only until combined.

Transfer the batter to the prepared Bundt pan and spread evenly. Gently tap the pan on the counter to release any large air pockets.

Bake for approximately 45–55 minutes, or until a toothpick inserted into the thickest portion of the cake comes out clean or with a few moist crumbs.

While the cake bakes, combine the maple syrup, water, vanilla extract, and salt in a small saucepan over low heat. Stir until warmed and combined. Remove from the heat.

Remove the cake from the oven and allow it to cool in the pan for approximately 5-10 minutes.

Using a thin wooden skewer, poke holes throughout the exposed surface of the warm cake. Slowly brush or spoon the maple syrup soak over the cake, allowing it to absorb between additions. Use only as much syrup as the cake comfortably absorbs.

Allow the cake to rest for another 5 minutes before carefully inverting it onto a wire rack. Brush additional syrup over the exposed cake if desired. Allow to cool completely before glazing.

In a medium bowl, whisk together the sifted powdered sugar, pure maple syrup, vanilla bean paste, and salt until smooth.

Add milk or heavy cream, 1 teaspoon at a time, until the glaze reaches a thick but pourable consistency.

Drizzle the glaze generously over the completely cooled Bundt cake, allowing it to drip naturally down the sides.

Allow the glaze to set for approximately 15–20 minutes before slicing and serving.