Preheat oven to 350°F and lightly grease two baking sheets.
In a large bowl, combine cheeses and yogurt; mix well. Add eggs and mix with spoon until mixture is loose but still lumpy. Unwrap phyllo and cut sheets in half lengthwise. Cover one stack with damp paper towels, until ready to use. Remove sheet from the uncovered stack, using a pastry brush, butter the sheet being careful not to tear the dough. Position the sheet vertically and drop a tablespoon of filling two inches from bottom edge, in the center. Fold the bottom edge up to cover the filling. Fold left edge to the center, creating a flap of about two inches wide. Fold right edge over the left flap but do not pass left edge; resulting in a strip about 3-inches wide. Starting with the lower left corner, fold over to the right edge to form a triangle. Continue folding up, then over, maintaining the triangle until you reach the end of the strip. Continue with remaining filling and dough sheets.
Place triangles on baking sheets and brush with butter. Bake until golden and flaky, about 15 minutes. Cool for 5 minutes prior to serving. Makes about 60 triangles.
Approximate Nutrient Analysis per tiropites (assumes 1 tablespoon unsalted butter per phyllo sheet):
160 calories, 12 g fat, 7 g saturated fat, 45 mg cholesterol, 200 mg sodium, 9 g carbohydrate, 0 g fiber, 1 g sugar, 4 g protein