Preheat oven to 315 degrees Fahrenheit.
Lightly butter and flour 2 bread loaf pans. Set aside.
In a large bowl, mix together flour, baking soda, and salt. Set aside.
In a stand mixer, cream together butter and sugar, until light and fluffy.
Add vanilla extract, and mix until combined.
Add eggs, one at a time, mixing well after each addition.
Slowly add in flour mixture, in 1/2 cup increments, mixing well after each addition. Mix until combined.
Mix in crème fraîche (or sour cream) until fully incorporated.
Pour half of the batter into each of the prepared pans.
Bake the cakes in the oven for one hour. Check the cake for doneness. Cake is ready when a toothpick inserted comes out clean.
Turn cakes out onto a wire rack for cooling. Avoid allowing them to cool in the pan, as this will soften the outer crust.