Bundt cake featuring a vanilla bean and buttermilk batter with a pecan molasses center is baked to perfection, then topped with the most delicious bourbon buttermilk glaze. This is made even better when served with homemade whipped cream!
Preheat oven to 350 degrees. Spray a large Bundt pan generously with nonstick spray and dust with cake flour. Sift hazelnut meal, cake flour, baking powder, and salt into a medium bowl. In a separate large mixing bowl using an electric mixer, beat sugar, butter, and 2 teaspoons of vanilla paste until fluffy. Beat in 1 egg at a time. Mix in flour mixture in 3 additions, alternating with buttermilk in 2 additions. Transfer half of the batter to the prepared Bundt pan.
In a medium bowl, stir chopped pecans, corn syrup, molasses, and 2 teaspoons of vanilla paste, mix well. Add baking soda, mix again Stir pecan mixture into remaining cake batter (not in Bundt pan). Once combined, spoon pecan batter over batter in Bundt pan (do not swirl). Bake until toothpick comes out with dry crumbs attached, about 60 minutes. Transfer cake to rack to cool, at least 1 hour.
Stir water and baking soda in a small bowl, set aside. In a large heavy 10-12 quart Dutch oven over high heat, bring baker's sugar, buttermilk, butter, and corn syrup to a boil, stirring until it reduces, 10-12 minutes (it will bubble a lot). Turn down heat to medium, add baking soda (it will bubble a lot more). Boil sauce until golden and slightly thickened, 8 more minutes. Remove from heat and add bourbon and vanilla paste.
Invert cake onto platter, drizzle 3/4 to 1 cup glaze onto cake to soak. Rewarm remaining glaze and pour on each piece right before serving.
Serve with homemade whipped cream or vanilla ice cream, if desired.