Place a rack in the center of your oven and preheat the oven to 350 degrees F. Grease and flour a large (10 or 12-cup) bundt pan and set aside.
In a large mixing bowl, stir together the cake and pudding mixes. Add the milk and water and stir to combine. Beat in the eggs one at a time, combing well after each, then add the butter and vanilla extracts. Beat for 6 minutes at high speed.
In a small bowl, stir together the streusel ingredients: granulated sugar, cinnamon, and pecans.
Pour half of the batter into the prepared pan, sprinkle with all of the cinnamon-sugar mixture, then pour the remaining batter over the top.
Bake the cake in the center of the oven until golden and a skewer inserted in the center comes out clean, 50 to 60 minutes. Set the pan on a wire rack and let cool for 8 minutes, then turn the cake out of the pan and let cool completely.
To make the glaze, beat together the powdered sugar, milk, butter extract, and vanilla extract until smooth. Drizzle over the cooled cake. Slice and serve.
Notes
TO STORE: Store leftover butter bundt coffee cake well-wrapped at room temperature for up to 1 week.
TO FREEZE: Freeze bundt cake in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before serving.