In a bowl of a standing mixer mix together flours, sugar, baking powder, and salt. Cut the butter into large pieces and add to the flour mix mixing at low speed.
Once the flour mix is hydrated and there are no large pieces of butter add the yolk, molasses, and vanilla and mix until sticky dough forms.
Divide dough into two. Wrap with plastic wrap and refrigerate/ freeze until ready to use.
Once ready to use line the bottom of 8" x 3" round or loaf pan with parchment paper and grease the sides of the pan.
Roll one half of the dough between two pieces of plastic wrap to about the same size as the pan.
Peel the top piece of the plastic wrap and use the bottom piece to place the rolled crust in the pan. Remove the plastic wrap and use your fingers to tuck any excess dough or fill any empty edges.
Use a fork to pierce the dough and gently spread the fig jam. Set aside while making the cake.
In a medium bowl sift the flour, baking powder, and baking soda. Set aside.
Measure the sour cream and fig paste in a medium bowl and mix to combine. Set aside.
In a bowl of a standing mixer fitted with the paddle attachment beat butter, brown sugar, sugar, and molasses on medium-high for 4-5 minutes. Scrape the sides and bottom of the bowl 2-3 times.
Slowly drizzle the oil and mix for additional 3-4 minutes. Until light and fluffy.
Add the eggs, one at a time waiting for each egg to fully incorporate before adding the next.
Scrape the sides and bottom of the bowl then add the flour mix in three additions alternating with the sour cream mix.
Right after adding the third portion of the flour, turn mixer off and complete blending with a rubber spatula.
Fold in chopped figs.
Pour batter on top of the crust and fig paste layers and bake for 40-45 minutes or until a toothpick comes out clean from the center of the cake.
Once the cake has cooled remove from pan, place on a serving dish and top with walnuts.
In a medium pan bring the corn syrup and honey to a boil. Remove from heat and add the butter, let melt.
Pour the warm syrup on top of the walnut and stir to distribute.