In a medium bowl, combine the flour, baking powder, baking soda and salt.
In a separate mixing bowl, beat together the butter and brown sugar until light and fluffy.
Add the eggs one at a time, beating for a minute or two, scraping the sides and bottom of the bowl between additions. Mix in the maple syrup.
Add half of the flour mixture, followed by the sour cream, vanilla, and maple flavor, and finally the remaining flour mixture. Mix until just combined, scraping the sides and bottom of bowl between each addition.
Scoop the batter into a greased and floured bundt pan and bake 25-50 minutes at 350 until a toothpick inserted in the center comes out clean.
Allow the cake to cool in the pan for 10 minutes (you are prepping the glaze during this time) then turn out onto a serving plate.
2 T unsalted butter
1/4 C Maplecrest maple syrup
1/4 C dark rum
To make the Glaze:
While the cake is cooling in the pan, combine the glaze ingredients in a medium saucepan. Bring to a rapid boil, then reduce the heat to simmer and cook for 5-8 minutes, until it thickens to a syrupy consistency. Remove the pan from the heat.
Brush or slowly pour the hot glaze over the warm cake. Allow the cake to cool completely before serving.