Cream together shortening, sugar, and vanilla. Add eggs, one at a time, and beat well after each. Sift together flour, baking powder, and baking soda. add 1/3 dry ingredients to batter, then 1/3 sour cream. Repeat additions of dry ingredients and sour cream two more times, beating only until incorporated after each addition.
For topping: mix with a fork the butter, brown sugar, cinnamon, and pecans. Grease a 9x13-inch pan. Put half the batter in the pan, then half the topping, remaining batter, and remaining topping.
Bake at 350 for 28 minutes in a metal pan, or at 325 for 30-35 minutes in a pyrex pan.