Preheat oven to 325°F.
In a mixer, cream together butter and 1 cup sugar for 2-3 minutes. Add in egg and vanilla extract and mix until incorporated.
In a separate bowl, whisk together flour, baking soda, and salt.
Alternate between adding flour mixture and buttermilk to the mixer and stir together until just combined.
In a separate bowl, mix remaining ¼ cup sugar and cinnamon together and set aside.
Butter inside of loaf pan and pour in half of the batter. Sprinkle the cinnamon-sugar mixture over the batter and then top with remaining batter.
Place loaf pan in oven and bake for 50-60 minutes, or until a toothpick inserted in center comes out clean. Remove from the oven and let cool.
Melt and heat the butter in a medium saucepan over medium heat until it is golden brown in color (be careful not to burn), about 5 minutes.
Turn heat to low. Add and whisk in powdered sugar and cream until well blended and sugar is dissolved.
Remove pan from the heat; add vanilla and stir mixture for about three minutes.
Place the frosting in the refrigerator for about 10 minutes until the frosting is cool and thick. If frosting thickens too much, add another Tablespoon cream.
This recipe will yield enough for a 2 layer 9-inch cake.