Line a baking sheet with parchment paper, and preheat the oven to 350 F.
In a large skillet, saute the red onion in olive over medium high heat until translucent. Add the minced garlic and cook for one minute until fragrant.
Mix in the chopped spinach and flour. Cook until almost all the liquid has evaporated. Remove from heat and let it cool down.
Mix in the beaten eggs, crumbled feta cheese, chopped fresh dill, salt, and pepper.
Place the phyllo dough on a dry surface and cut it into 2.5-inch wide strips. Cover the strips with a damp towel.
Take two strips and brush the first one with melted butter. Place the second one on top and brush it with melted butter as well.
Place one tablespoon of filling at the top of the strip and fold into a triangle. Keep folding the dough in a triangle shape until you reach the bottom.
Do the same with the rest of the stips and place the triangles on the baking sheet.
Brush the triangles with melted butter, sprinkle sesame seeds on top, and bake for 30-35 mins or until golden brown.