Crack the eggs into a separate bowl. Put the flour, baking powder, baking, soda, and salt, together in another bowl and whisk for 30 seconds to ensure the ingredients are well combined. (NOTE: If not weighing the flour, measure it by spooning the flour into the measuring cup and use a butter knife to level the flour).
Place the dark brown sugar, granulated sugar, butter and ground cinnamon in the bowl of a stand mixer outfitted with a paddle attachment. Mix the ingredients on medium low until they are just combined and then increase the speed to medium-high beat the mixture on medium-high speed until fluffy, about 6 minutes. After the first 3 minutes stop the mixer and scrape the sides and bottom of the bowl. Scrape off any butter that may be on the paddle.
Scrape down the bowl. Add eggs one at a time on low speed and then increase to medium until each egg is well incorporated. Stop the mixer after adding the first 2 eggs and scrape the bowl from the bottom to ensure the ingredients are well mixed. Add the remaining 2 eggs and scrape the sides and bottom of the bowl after mixing in the last egg.
Add 1/3 of the flour mixture and mix on low speed until well combined, but do not over mix. Add half of the sour cream and mix on medium speed until well combined. Add half the remaining flour mixture, mix on low speed and then add the remaining sour cream. Add the last of the flour and mix on low speed until just combined. Scrape the sides and bottom of the bowl and mix on low speed for about 20 seconds to ensure all the ingredients are well mixed.
Scoop 1/2 the batter into the prepared bundt pan. If using the Elegant Bundt pan, or another bundt pan with similar deep grooves tap the pan against the counter three times to settle the batter into the grooves of the pan. Add about the half of the hazelnut fig jam to the cake batter in dollops across the surface. Use a butter knife to swirl the jam into the batter. Be careful not to touch the sides or bottom of the pan.
Add the remaining cake batter. Smooth across the top. Add the remaining hazelnut fig jam in dollops across the batter. Use a butter knife to swirl the jam into the batter. Smooth the top of the batter. Place the pan in the oven and bake for 40-45 minutes until a skewer inserted in the center comes out clean. When the cake bakes, a visible ring will form around the center of the cake. This ring is where you want to test the doneness of the cake.
Remove the cake from the oven and place the pan on a cooling rack. Allow the cake to cool for 15 minutes and then invert it on a cooling rack lined with a piece of parchment paper. Lining it with parchment paper will make it easier to move the cake to a cake plate later without it sticking. If you do not have parchment paper, lightly oil the cooling rack before inverting the cake.
Allow the cake to come to room temperature before glazing it with the chocolate glaze.