St. Louis Gooey Butter Cake from Scratch

Description
Available in almost every bakery and supermarket in the St. Louis area, this ooey, gooey coffee cake is unique in taste, texture and appearance.
 * Contributed by Catsrecipes Y-Group
 * Yield: 2 cakes; 10 to 12 servings each

Dough

 * ¼ cup warm water (110°F)
 * 4½ teaspoons instant yeast
 * ½ cup warm milk (110°F)
 * ⅓ cup granulated sugar
 * 2 teaspoons pure vanilla extract
 * ¼ cup (½ stick) unsalted butter, softened
 * 1 egg
 * ¼ teaspoon salt
 * 2½ cups all-purpose flour, divided

Gooey butter topping

 * 2½ cups granulated sugar
 * 1 cup (2 sticks) unsalted butter, softened
 * dash salt
 * 1 egg
 * ¼ cup light corn syrup
 * 2⅓ cups all-purpose flour
 * ¼ cup warm water (110°F)
 * 2 teaspoons pure vanilla extract
 * confectioners' sugar, for sprinkling

Dough

 * 1) Combine water and yeast in mixing bowl of electric mixer; hand-whisk to mix, then let stand a few minutes.
 * 2) Stir in milk, sugar, vanilla, butter, egg, salt, and 2 cups of the flour.
 * 3) Switch to dough hook and knead on slow speed, sprinkling in as much of the remaining ½ cup flour as needed, until dough is smooth, about 5 to 8 minutes.
 * 4) Cover bowl with a towel and let dough rise in warm, draft- free place 45 to 60 minutes, or until almost doubled.

Gooey butter topping

 * 1) Meanwhile, prepare gooey butter topping.
 * 2) Combine granulated sugar, butter, salt, egg, corn syrup, flour, water and vanilla in work bowl of food processor fitted with metal blade; process 20 to 30 seconds, or until mixture is a smooth paste (or beat with electric mixer until well mixed).

Assembly

 * 1) Generously spray two 9-inch square baking pans with nonstick cooking spray.
 * 2) Line a baking sheet with parchment paper.
 * 3) Gently punch down dough.
 * 4) Divide dough into two equal pieces.
 * 5) Press one portion into each prepared pan, pressing lightly to fit.
 * 6) Use fingertips to crimp edges about halfway up side of pan to make a border (so gooey butter will not run underneath).
 * 7) Use a fork to prick a few holes in dough to prevent bubbling (do not prick dough all the way through).
 * 8) Divide gooey butter into two equal portions; spread over dough in each pan.
 * 9) Let stand, uncovered, 25 minutes.
 * 10) Place pans on prepared baking sheet.
 * 11) Bake in preheated 375°F oven 20 minutes, then reduce heat to 350°F and bake 15 minutes.
 * 12) Topping should be bubbly and golden brown. Do not overbake; topping will not be gooey if cakes are baked too long.
 * 13) Remove pans from oven and transfer to wire racks to cool until the topping settles and cake is just a bit warmer than room temperature.
 * 14) Sprinkle tops with confectioners' sugar.
 * 15) Serve warm or at room temperature.