Preheat oven to 350 degrees. Coat a bundt pan with no stick cooking spray.
Combine melted butter, apple butter, brown sugar and oil in bowl and whisk until smooth. Add diced apples (or 1/2 c. raisins) buttermilk, egg, and vanilla and mix well. Add remainder of dry ingredients and mix until just combined.
Pour batter into bundt pan and bake 30-35 minutes, until knife inserted in center comes out clean. Let cool about 10 minutes, invert on serving platter and drizzle glaze over top.
To make the glaze:
Combine powdered sugar, apple liqueur and milk in small bowl, whisk well, then drizzle over cake.