Grease bundt pan with butter wrappers or nonstick spray.
Beat softened butter with brown sugar until well blended.
Add in 3 eggs one at a time, beating well after each one.
Add in cocoa, baking soda and salt; mix to combine. Gradually add in flour.
Add 1 cup cold water and beat on high for 30 seconds.
Pour into greased pan and bake at 350 for 45-50 minutes, or until a toothpick inserted comes out clean. Cool.
For the filling. In a microwave (or preferably a double boiler), combine the chocolate and butter in a large bowl. Microwave in 30 second increments, stirring after each time, until chocolate and butter are fully melted and smooth. Stir in Kahlua.
Finishing: Cut cooled cake into three layers, On each layer, drizzle 1/4 cup Kahlua and 1/3 cup of filling. Add the next layer and repeat. Add the last layer and pour the remaining glaze over the top.