Based on a traditional yellow cake mix recipe, this cinnamon and pecan coffee cake is the perfect breakfast recipe! Baked in a Bundt pan with a simple glaze on top, anyone who eats this will want the recipe for themself!
Preheat the oven to 350°F. Grease a bundt pan with baking spray and set it aside.
In the bowl of an electric mixer, combine the flour, cornstarch, sugar, baking powder, and salt. Mix on low speed for 30 seconds to combine. Add the room temperature butter 1 tbsp at a time and allow each piece to incorporate before adding the next, 2-3 minutes, until the mixture looks like wet sand. Add the oil and mix on low.
In a large measuring glass, combine the eggs, yolks, milk, and vanilla extract. Whisk to combine. With the mixer on low speed, add half of the wet mixture to the mixer. Mix for 1 minute and add the sour cream. Continue to mix for 1 minute, then add the remaining milk mixture. Mix until just combined, 1 minute, and turn the mixer off.
In a small bowl, combine ¾ cup of toasted pecans, ½ cup of sugar, and the cinnamon. Stir to combine. Pour roughly ¾ of the batter into the prepared Bundt pan. Sprinkle about ¾ of the sugar mixture on top. Repeat with the remaining batter and sugar mixture. Use a knife inserted all the way to the bottom of the pan and make figure-eight patterns to combine the sugar and batter slightly.
Bake in the preheated oven until the cake is golden and a skewer inserted in the middle comes out mostly clean, 45-55 minutes. Remove the cake from the oven and cool in the pan for 10 minutes. Then invert on a cooling rack for 40 minutes to finish cooling.
While cooling, combine the powdered sugar, cinnamon, vanilla extract, and milk. Whisk until smooth and drizzle over the cooled cake. Top with the remaining nuts and serve.