Bake cake 55 minutes, or until toothpick inserted in center comes out clean. Remove from oven, and cool.
Meanwhile, to make pecan Praline Frosting: Place brown sugar and heavy cream in saucepan, and bring to a boil over medium heat. Reduce heat to low, and cook 10 minutes. Remove from heat, and add butter and vanilla. Set aside to cool to warm, but do not stir. Place frosting in bowl, and beat in confectioner's sugar, a little at a time, until spreading consistency. Fold in chopped nuts, saving pecan halves to place decoratively around top of cake.
Place bottom cake layer on plate, and spread frosting on it, letting frosting drizzle down side of cake. Repeat with remaining two layers. Alternatively, frost each cake layer, both sides and top. If frosting begins to harden, dip spatula into warm water to make frosting easier to spread.