Boston Cream Pie Poke Cake

Steps

1. Center a rack in oven and heat to 350 degrees. Grease a 9x13" baking pan and set aside.
2. In a medium bowl, whisk cake mix, water, eggs, and oil until smooth. Transfer to prepared pan and smooth top. Bake until a toothpick inserted in center of cake comes out clean, 25 to 30 minutes, rotating halfway through.
3. Let cool 5 minutes, then use the handle of a wooden spoon to poke holes all over cake, spacing them about 1" apart and poking all the way to the bottom of pan.
4. In a medium bowl, whisk pudding mix, 1 2/3 cups heavy cream, the milk, and 1 teaspoon vanilla until combined, about 30 seconds. Immediately pour mixture onto warm cake and spread into an even layer, covering all the holes. Refrigerate until pudding is set, 1 to 2 hours.
5. Combine chocolate morsels and remaining 3/4 teaspoon vanilla in a medium bowl and set aside. Bring remaining 2/3 cup heavy cream, the corn syrup, and salt to a simmer in a small saucepan, then pour over chocolate mixture and let sit 2 minutes without stirring.
6. Stir chocolate mixture until smooth and glossy, then pour over chilled cake and spread into an even layer. Refrigerate until ganache is set, about 1 hour, before serving.