Using hand mixer, mix cream cheese and mayonnaise until smooth.
Stir in chives, dill, lemon zest, lemon juice, salt, and pepper.
Spread the cream cheese mixture onto one side of each slice of bread.
Layer the cucumbers on top of the cream cheese mixture. Top with more chives, dill, and remaining bread slice.
Carefully press down on the sandwich as you cut into 4 squares or 2 triangles.
Top each sandwich with a thin slice of cucumber and dill. Serve immediately or cover and store in the fridge for up to 24 hours.