Heat two tablespoons of olive oil in a skillet over medium heat. Add finely chopped onion and sliced green onions, sauté for 3-4 minutes until translucent. Stir in minced garlic and cook for an additional minute, then add spinach, stirring until just wilted.

Transfer sautéed mixture to a bowl, allow cooling slightly. Add parsley, dill, mint, crumbled feta, beaten eggs, season with salt and pepper. Mix thoroughly and set aside.

Unroll phyllo dough, keeping it covered with a damp towel. Preheat oven to 375°F (190°C). Use a pastry brush for applying melted butter.

For casserole, brush a 9x13 inch baking dish with melted butter. Layer 8-10 sheets of phyllo, brushing each with butter. Spread spinach filling evenly, cover with additional phyllo, buttering each layer. Tuck edges and score the top. Bake for 40-50 minutes until golden.

For Spanakopita rolls, take two sheets of phyllo, brush with butter, place filling at one end, roll tightly, seam-side down on a lined baking sheet. Bake for 20-25 minutes until golden.

For bites, cut phyllo into strips, place filling, fold into triangles, brush tops with butter. Bake for 15-20 minutes until golden brown.

Remove from oven, let cool slightly. Serve warm or at room temperature, perhaps with Greek salad or tzatziki.