Preheat oven to 180°C/350°F. Line 2 trays with baking paper and set aside.
If using fresh spinach- Place spinach in a bowl & microwave in 45 seconds intervals until it has wilted. Set aside for 5 minutes or cool enough to handle.
Using a clean dish cloth or paper towel, place spinach inside and squeeze with your hands to remove excess moisture until it is quite dry. You'll be amazed how much water is released. Transfer to a chopping board and chop.
In a large bowl add rest of filling ingredients and mix together until smooth. set aside.
On a clean work surface, lay 1 sheet of filo pastry & brush lightly with butter or spray with olive oil spray. Keep remaining sheets covered with a damp tea towel so they don’t dry out. Place a second sheet of pastry on top and repeat butter/oil step and top with a third layer. Repeat this step to use up the remaining filo pastry sheets. You should have 4 sets of pastry that each has 3 layers.
Lay one set of the layered pastry on your work surface or cutting board, with short edge facing you. Using a sharp knife, slice the sheet into 3 even rectangle strips.
Taking one strip, place 1 heaped tablespoon of filling onto the bottom right corner of the filo strip. Fold the bottom corner over to make a triangle shape, gently flattening the ricotta mixture. Continue to fold the pastry over itself, working your way up the sheet until a neat triangle is formed. Be careful not to squeeze the mixture out.
Place onto the baking trays & repeat steps for remaining pastry sheets.
Lightly brush triangles with butter or spray with olive oil before baking for 15-20 minutes or until the pastry is golden brown.