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Preheat the oven to 375 F. Line a 9X13 baking pan with parchment paper and grease it. Set aside.
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Sift the flour into a medium sized bowl. Whisk in the salt and baking soda. Set aside.
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Using a stand or handheld mixer, beat the butter until creamy. Add the sugar in 5 installations, beating after each one. Be sure to scrape the sides and bottom of the bowl as needed.
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Add the egg yolks, one at a time, beat well after each addition. Be sure to scrape the sides and bottom of the bowl as needed.
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Beat in the ground vanilla beans and Bourbon.
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Add the flour mixture and yogurt in 3 and 2 additions, respectively, alternating between the 2 and beginning and ending with the flour mixture. Mix on low speed.
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Switch to using a spatula by hand.
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Whip the egg whites to hold stiff peaks. Place a dollop of the egg whites into the cake batter and mix it in to loosen it. Then fold the remaining egg whites into the batter, being careful to not overly deflate the egg whites.
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Scrape the batter into the prepared pan and smooth the top even.
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Bake for 10 minutes, and then reduce the heat to 350 F. Mine took much longer than expected--bake another 30 minutes, and if it is still quite gooey, place foil loosely on top of the cake (that will prevent it getting too dark) and bake another 10 minutes. The cake is ready when a cake tester inserted into the center of the cake comes out clean or with only a few crumbs attached.
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While the cake is baking, place the soaking syrup ingredients into a sauce pan. Bring the mixture to a boil, stirring occasionally. Once the sugar is dissolved, let it boil for 5 minutes. Then take it off the heat and set aside.
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When the cake is done, take it out of the oven and place it on a cooling rack for 10 minutes.
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After it has cooled for 10 minutes, poke holes all over the cake (not riddled with holes, maybe 3 inches apart?). Brush half of the syrup over the cake and into the holes.
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Let the cake cool another 10 minutes. Brush the remaining syrup over the top and into the holes.
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Let the cake cool completely before removing by the parchment paper and slicing.