In a mixing bowl, combine crumbled feta cheese and grated kefalograviera cheese. Season generously with freshly cracked pepper to taste. Mix until well combined and set aside.

Take one phyllo sheet and lay it flat. Brush a generous layer of olive oil over the sheet. Spread a portion of the cheese mixture down one edge.

Starting from the long edge with the cheese filling, roll the phyllo sheets into a tight log shape. Tuck the ends as you go.

Wrap the rolled phyllo logs tightly in plastic wrap and freeze for at least one hour.

Preheat your oven to 350°F (175°C). Remove the frozen logs from the freezer and let them sit for about 10 minutes to soften.

Using a sharp knife, slice the phyllo logs into 1-inch pieces. Arrange the cut pieces on a greased baking sheet.

Bake in the preheated oven for 20-30 minutes until golden brown and crispy.