Prep the Oven & Bundt Pan: Preheat your oven to 350°F (175°C) with a rack in the lower-middle position. Generously grease a 10 to 12-cup heavy fluted bundt cake pan with nonstick baking spray with flour or melted shortening, being sure to coat every fluted groove and the center tube thoroughly.

Make the Caramel Pecan Base: In a medium bowl, whisk together the melted unsalted butter, packed dark brown sugar, maple syrup, heavy cream, and flaky sea salt until smooth and glossy. Pour the warm caramel mixture evenly into the bottom of the prepared bundt pan. Scatter the toasted pecan halves evenly over the caramel layer, gently pressing some into the bottom grooves.

Whisk Dry Ingredients: In a separate large bowl, whisk together the all-purpose flour, baking powder, baking soda, fine sea salt, ground cinnamon, and freshly grated nutmeg until well aerated and uniform. Set aside.

Cream Butter & Sugars: In a stand mixer fitted with the paddle attachment (or using an electric hand mixer), beat the softened butter, granulated sugar, and light brown sugar on medium-high speed for 3 to 4 minutes until light, pale, and fluffy.

Add Eggs & Flavoring: Add the eggs one at a time, beating well after each addition and scraping down the sides and bottom of the bowl. Beat in the pure vanilla bean paste.

Alternate Wet & Dry: In a glass measuring cup, stir together the room temperature sour cream and whole milk. With the mixer on low speed, add the dry ingredients in three additions, alternating with the sour cream-milk mixture in two additions, mixing just until combined and no flour streaks remain (do not overmix!).

Layer & Smooth: Gently spoon the thick cake batter over the pecan caramel layer in the bundt pan, being careful not to disturb the pecans. Smooth the top evenly with an offset spatula.

Bake: Bake at 350°F (175°C) for 50 to 58 minutes, or until a long wooden skewer or cake tester inserted deep into the center of the cake crumb comes out clean (a little sticky caramel from the bottom is fine). If the top browns too quickly during the last 15 minutes, tent loosely with a sheet of aluminum foil.

The Crucial Inversion: Remove the cake from the oven and set it on a wire cooling rack for EXACTLY 10 to 12 minutes (do not wait longer, or the caramel will cool and stick to the pan!). Place an inverted rimmed serving platter or cake stand firmly over the bundt pan. Using oven mitts, firmly grasp both the pan and platter together and swiftly invert. Tap the top and sides of the pan gently, then slowly lift the pan off to reveal the glistening praline crown! Use a spatula to scrape any remaining warm caramel and pecans from the pan onto the cake.

Cool & Serve: Allow the cake to cool for at least 20 minutes so the warm caramel sets slightly. Slice into generous wedges and serve warm with a scoop of vanilla bean ice cream or freshly whipped cream!