Add sugar and beat until light and fluffy, about 3 minutes.
Add eggs, one at a time, beating until well combined.
Measure the flour, baking powder, baking soda, salt, and cocoa powder into a small bowl and whisk to combine.
In another small bowl, measure out the milk and vanilla and stir to combine.
Add about a third of the dry ingredients to the butter/sugar and beat to combine.
Add about half of the milk/vanilla and beat to combine.
Continue adding, alternating between dry and wet and finishing with the dry.
Make the fun gooey part.
To make the fun gooey part
In a small saucepan, combine sugar, corn syrup, and butter.
Cook over medium heat, stirring constantly, until the butter melts and the sugar dissolves.
Cool slightly.
In a large bowl, combine eggs, bourbon, vanilla, and salt. Mix well.
Slowly pour the sugar mixture into the egg mixture, whisking constantly.
Stir in chocolate chips and pecans.
To complete the cupcake
Fold 3/4 of the fun gooey part into the chocolate cupcake batter. You don't need to mix it well, just give it a nice stir.
Fill cupcake liners about halfway.
Use up the remaining 1/4 of the filling by putting an additional spoonful or two of the fun gooey part on top of each cupcake, being careful not to fill them more than 3/4.