The result of a long-ago happy accident in a St. Louis bakery, this unique recipe pairs a yeasted cake base with a butterscotch-like topping. The cake's undulating, uneven top surface gives it a comfortingly rustic appearance.
Grease a 9" x 13" pan.
To make the cake: In a small bowl, combine the yeast, milk, and warm water. Set aside. In a large mixing bowl, beat together the butter, sugar, and salt. Scrape the bowl, then beat in the egg.
Add the flour and the yeast mixture, alternating between each, beginning and ending with the flour. Mix well, then scrape the bowl once more. Mix at medium speed for 4 to 5 minutes.
Place the dough in the prepared pan and press it out to cover the bottom. Cover and set aside to rise until almost doubled, about 2 1/2 hours.
Towards the end of the rising time, preheat the oven to 350°F.
To make the topping: In a small bowl, whisk together the corn syrup, water, and vanilla.
In a large mixing bowl, cream together the butter, sugar, and salt until light and fluffy. Scrape the bowl, then mix in the egg.
Add the flour alternately with the corn syrup mixture, beginning and ending with the flour. Scrape the bowl, mix for 30 seconds more, then spoon the topping over the risen dough.
Use an offset spatula to gently even out the top. Bake for 30 (if baking in metal) to 45 (if baking in ceramic or glass) minutes. The cake will rise and fall in waves and have a golden brown top, but still be liquid in the center when done.
Remove the cake from the oven and cool completely in the pan. Dust with confectioners' sugar before serving.
Store any leftovers, well wrapped, in the refrigerator for several days. Freeze for longer storage.
