In small bowl stir together flour, sugar, cinnamon, using 2 knives or pastry blender cut in the butter into course crumbs...set aside.
In large bowl, beat together butter and sugar until light and fluffy, beat in eggs 1 at a time, add vanilla. whisk together in another bowl the flour, baking powder, baking soda, salt, cinnamon and nutmeg. stir into butter mixture alternately with buttermilk.
Scrape one half the mixture into parchment lined paper 9 x 5 x 2 loaf pan, add half the streusel then the rest of the batter and top with rest of streusel. Bake at 325F oven for 55 to 60 minutes, or until wooden pick comes out clean when inserted into center of loaf. Let cool in pan for 10 minutes then remove from pan and cool on wire rack.