Preheat the oven to 425°F (220°C) and butter a baking dish.
In a medium bowl, stir together ground almonds, flour, and softened butter until smooth and combined.
Add salt, cayenne, lemon zest, lemon juice, and Worcestershire sauce to the almond mixture and mix well to form a spreadable paste.
Place the chicken breasts between two sheets of plastic wrap and pound lightly with a meat mallet or rolling pin to an even thickness.
Spread a generous layer of the almond butter mixture over each chicken breast, then sprinkle the slivered or sliced almonds evenly on top.
Arrange the prepared breasts in the buttered baking dish and bake for about 15 minutes, until the chicken is cooked through and the almonds are golden brown.
Remove from the oven and serve immediately.