In a medium bowl, stir the softened cream cheese and Greek yogurt until smooth.
Add the feta, spinach, scallions, dill, garlic powder and black pepper; mix until evenly combined.
Spread one quarter of the filling over each tortilla, leaving a 1/2-inch border at the edges.
Roll each tortilla up tightly, wrap in plastic wrap and refrigerate for at least 1 hour (up to 24 hours).
Trim the ragged ends, then slice each roll into 8 rounds with a serrated knife.
Arrange on a platter and serve chilled; refrigerate leftovers in a sealed container for up to 2 days.
