In a small bowl, using an electric hand mixer beat the cream cheese, mayonnaise, dill, garlic powder, and salt until smooth; set aside.

Peel the cucumber in strips and cut into 1/8-inch slices using a mandoline or sharp knife. Line a baking sheet with paper towels. Lay the cucumber slices over the paper towels in a single layer and blot the excess moisture on the top.

Cut the crust off each piece of bread to make squares.

To Assemble: Spread about 1 tablespoon cream cheese filling onto each piece of bread. Add thinly sliced cucumbers, fresh cracked pepper, and additional dill if desired. Place the second piece of bread on top then carefully cut into triangles or squares using a serrated knife.

Serve immediately or store in a covered container in the refrigerator for up to 24 hours.