In a large mixing bowl, cream butter and sugar until light and fluffy.

Add eggs and vanilla, beating until combined.

In a medium bowl, stir together flour, baking soda, and salt.

Add to the mixing bowl alternately with the buttermilk, beating until just combined.

Line two 9-inch round baking pans with parchment paper, and extend it slightly over the edge in two places, so that you can lift the coffee cake layer out of the pan easily after baking.

Divide the batter evenly among the cake pans.

In a small bowl, stir together sugar, pecans, and cinnamon.

Sprinkle evenly over the batter in the two cake pans.

Lightly swirl with a knife.

Bake at 350 degrees for 20-25 minutes, or until a toothpick inserted near the center comes out clean.

Cool completely.

In a small mixing bowl, beat cream cheese and butter til creamy.

Add vanilla and powdered sugar, beating until smooth.

Fold in whipped topping.

The cakes are pretty fragile and crumble easily. Gently remove one of the cake layers from the pan, and set it immediately onto a serving plate. Carefully remove the parchment paper from underneath.

Spread the cake with filling.

Gently remove the second cake layer from the pan, remove the parchment paper, and set it over the filling.

Cut and serve. Store leftovers in the refrigerator!