Preheat oven to 350F. Spray two 9X5X3 inch loaf pans with non stick cooking spray and line with parchment along the bottom and sides of the pan, keeping a little on the top to help pull the cake out
Sift flours, baking powder, baking soda and salt and set aside
In a stand mixer or food processor, whip or pulse sugar, eggs, lemon zest and lemon juice until combined. Add the melted butter slowly. Add the creme fraiche last and mix until combined.
Sprinkle in the flour in several additions, taking care not to overmix
Divide the batter evenly between your loaf pans and bake for 35 to 40 minutes, rotating a couple of times during baking. Check to see if the cake is fully baked by inserting a toothpick into the centre, making sure it comes out clean.
Remove from pans and let cool for 15 minutes
In the meantime make the lemon syrup by heating lemon juice and sugar on low heat until the sugar dissolves. Take off heat and add the limoncello
Place wire rack over a tray or parchment paper. Poke holes in the cake and brush the lemon syrup over the cake until most of the liquid has absorbed.
Let cakes cool completely before applying the lemon glaze
To make the glaze, whisk together sugar, and some of the lemon juice. If the glaze is too thick add some more lemon juice until you reach the right consistency.