• Preheat the oven to 400F with a rack in the middle position. Have two 12-cavity muffin tins ready. Using 1 muffin tin works, making the recipe in 2 batches.

Making the Bread Cups

• Melt down ¼ cup of the butter in a small dish and have a pastry brush ready.
• Using a round cutter (or a drinking glass), cut out as big of a circle as you can from each slice of bread.
• Flatten out each bread round with a rolling pin or by pressing it down with your hand.
• Brush one side of each flattened bread round with melted butter. Gently press each buttered round in the muffin tin cavities. Gently do so by folding in the edges to prevent any cracking while pressing the round into the molds to create a cup. The sides will not reach the top of the mold cavity, this is ok.
• Place the prepared bread cups into the preheated oven for 5 minutes, until lightly toasted. When ready, remove from the oven and reserve.

Making the Crab Filling

• Start by making the white sauce. In a large saucepan on medium heat, add the remaining ¼ cup of butter.
• Once the butter has melted, whisk in the flour to create a smooth mixture. Proceed by whisking in the milk. Whisk consistently until the sauce thickens and starts to simmer. Turn off the heat.
• Add the grated cheese, prepared onion, mustard, Worcestershire sauce, lemon zest, parsley, seasoning and crab meat. Fold everything together until combined.

Assemble the Crab Puffs

• Divide the filling evenly between the 24 toasted bread cups.
• Place back into the oven for 15-20 minutes, or until nice and golden.
• Remove from the oven and allow to rest for 10 minutes before serving. The filling will still be somewhat liquid, and very hot, when coming out of the oven.