Look over the cherries to make sure all the pits were removed. Combine cherries and brandy in a small bowl. Microwave on high power for 30 seconds. Let stand until cool, about 30 minutes. Drain.
Grease a 3 1/2-quart slow cooker with butter. Cover the bottom with 1/2 of the bread cubes. Scatter 1/2 of the cherries and white chocolate chips on top. Layer remaining bread cubes, cherries, and chocolate on top.
Whisk eggs and sugar in a medium bowl until smooth. Whisk in half-and-half and vanilla until blended. Carefully pour over the bread mixture, gently pressing down on the bread to immerse in liquid.
Cook on High, without lifting the lid, until set and puffed, about 1 hour 15 minutes. Serve warm or at room temperature.