Line a large sheet pan with parchment paper. Set aside
In the bowl, using an electric hand mixer, cream the butter and the sugar.
Grind the pistachios finely in a mini food processor.
Add the ground nuts, then add the egg.
Add the vanilla and rum. Mix well
Transfer to a small container, and refrigerate overnight (or until cold).
Divide the puff pastry in 2.
Roll one half to a 12-inch circle (or a little bigger, and trim to a 12-inch circle). Place on the prepared sheet pan.
Spoon the filling into the center of the disc, leaving the outer edge free for egg wash.
Place the black-eyed pea in the filling, close to the edge, and in the direction that you would cut the galette (to avoid slicing it in half).
Prepare the egg wash by mixing the egg with a little water and a pinch of salt to thin it out.
Brush the edges with a thin layer of egg wash.
Roll the other half to a slightly larger disc. And place on top.
Press down the edges really, really well!
Trim the edges to make them pretty, if you’d like.
Brush the top pastry lightly and evenly with egg wash. Let stand 1 minute to dry a little, then coat it again.
Draw pretty patterns with a knife (don’t pierce the pastry!) on the top pastry..
Pierce the pastry to allow for venting.
Refrigerate for at least 1 hour.
Preheat the oven to 375 ºF.
Bake the galette at 375°F for 45 to 50 minutes.
Let cool completely before serving.
The person that gets the slice with the bean gets to wear the crown!