Preheat oven to 350 degrees. Line a 9 x 13 inch cake pan with parchment.
In a bowl, cream the butter, brown sugar, sugar, and pumpkin butter until smooth and fluffy, about 2-3 minutes. Whip in the egg, then the vanilla. Add the flour, oats, baking soda, cinnamon, ginger, cloves, and salt. Fold in the white chocolate chips or chunks with a spatula.
Dump the dough into the prepared cake pan and spread/pat in an even layer. Bake 25-30 minutes until the edges are golden and the center is no longer shiny. Cool at least 25 minutes before slicing and serving.