01 -
Preheat the oven to 175°C. Grease and flour two 23-centimeter round cake pans.
02 -
In a medium bowl, whisk together the flour, baking soda, cinnamon, allspice, nutmeg, and salt. Set aside.
03 -
In a large bowl, cream the unsalted butter, granulated sugar, and brown sugar with an electric mixer until light and fluffy.
04 -
Add the eggs to the butter mixture one at a time, mixing well after each addition.
05 -
Mix in the seedless blackberry jam until fully integrated.
06 -
Add the flour mixture to the batter in thirds, alternating with the buttermilk, beginning and ending with the flour. Mix until just combined.
07 -
Gently fold in the chopped pecans and raisins if desired.
08 -
Divide the batter evenly between the prepared cake pans. Bake for 35–40 minutes, or until a toothpick inserted into the center comes out clean.
09 -
Let the cakes cool in the pans for 10 minutes. Invert onto wire racks and allow to cool completely.
10 -
In a saucepan over medium heat, melt the butter. Stir in the brown sugar and cook for 2–3 minutes until bubbly. Add the milk, bring to a gentle boil, then remove from heat and cool for 5 minutes.
11 -
Gradually whisk in the sifted powdered sugar and vanilla extract until the frosting is smooth and spreadable.
12 -
Place one cake layer on a serving plate and cover with caramel frosting. Top with the second layer and frost the top and sides generously.