Lemon Buttermilk Cake with Blackberry Swirl
1/2 C (1 stick) butter, softened
1 C white sugar
1 tsp lemon zest
1 Tbsp lemon juice
1 1/4 C all-purpose flour
3/4 tsp baking powder
1/4 tsp baking soda
1/8 tsp salt
1/2 C buttermilk
1/4 C blackberry jam
Beat butter and sugar together. Add eggs one at a time; fully incorporate. Add lemon zest and juice. (The amount of zest and juice are roughly the equivalent of 1 large lemon.)
In a separate bowl, combine flour, baking powder and soda, and salt. Stir gently with a fork or whisk to break up lumps. Sift if the mixture is still lumpy.
Alternately add flour mixture and buttermilk to butter and egg mixture. Do NOT over mix!
Into each of 2 sterilized and greased canning jars, add two large spoonfuls of the batter. Add 1 heaping teaspoon of jam to each jar. Do this two more times to create 3 layers. (Jars should not be more than 2/3 full.) Take a skewer or a long skinny spoon handle and swirl the batter and jam together. Do not mix too much.
Bake at 350 deg F for 30-35 minutes, until a toothpick inserted into the center comes out clean. Within 3 minutes of removing cakes from the oven, close with 2 part canning lid. In about 5-7 minutes you'll hear the lid pop, this means it is vacuum sealed. Allow to cool at room temp.