Preheat oven to 350°F, and line two large cookies sheets with parchment paper.
Add the butter, peanut butter, brown sugar, and sugar to a large bowl, and mix until combined. Then mix in the egg.
Mix in the flour and baking soda.
Fold in the chopped Cadbury chocolate eggs (reserve about ¼ cup of the larger pieces to press into the top of the dough balls) and peanut butter morsels. The cookie dough will be thick but not too dry. And it shouldn't be sticky.
Use a cookie scoop to drop level scoops of dough onto the parchment-lined cookie sheets about 2 inches apart. Then, press some large pieces of the mini-eggs and some extra peanut butter morsels.
Bake for 15 minutes or until they have spread to about 2 inches and are browning around the edges.
Let the cookies cool on the cookie sheets for 15 minutes, then transfer to a wire rack to cool completely or serve warm.