Our all-time favorite coffee cake. The boys prefer it without the pecans, but I love the texture of the nuts as part of the filling. Either way, it's a wonderful, moist and luscious cake.
Combine cake ingredients in a large mixing bowl. Using an electric mixer, beat ingredients for 2 minutes, scraping bowl half way through. Meanwhile, combine the filling ingredients and reserve.
Pour half of the prepared cake batter into a greased 9 x 13 pan. Sprinkle the prepared filling mixture over the batter, then use a butter knife to swirl the filling into the batter. Pour the remaining cake batter over the top of the filling.
Bake the cake, uncovered, on the center rack of the preheated oven for 25-30 minutes, or until a cake tester or knife inserted into the center of the cake comes out clean.
While the cake is baking, combine the icing ingredients in a bowl and whisk until smooth; pour the prepared icing over the hot cake immediately after it comes out of the oven. While the cake is still hot, cover with foil and let cool completely.