Preheat oven to 325 deg. F. Grease and flour a bundt pan. In a med. bowl sift together flour, baking powder, and salt. Set aside.
Cream soften butter and cream cheese on high speed. Gradually add sugar and continue to beat until well mixed and fluffy. Add eggs, one at a time beating well after each addition.
Add dry ingredients and buttermilk to mixture. Mix well. Stir in vanilla and butter flavorings. Mix well. Lastly, add 1/2 c. of dark rum and mix on high until well blended.
Layer the bottom of the bundt pan with the pecans/walnuts. Pour batter on top of the nuts. Bake in oven for 1 hour or until toothpick comes out clean. When done, remove from oven and let cool for a few minutes. Turn out onto serving plate. Pick cake to allow glaze to soak through.
To prepare GLAZE: Melt butter in a small saucepan. Add water and sugar and boil for 5 minutes. Constantly stir mixture. Remove from heat and stir in rum. Patiently drizzle glaze over the cake allowing the cake to absorb the glaze between additions.
This cake is best served the next day once the buttered rum glaze has had an opportunity to infuse the cake.