Preheat the oven to 160°C fan / 180°C conventional, with oven rack on the bottom rung.
Assemble required equipment before opening the filo package.
Melt the butter in the microwave on a medium in bursts of 10 seconds.
Open the filo package and keep the filo sheets under a tea towel that has been lightly sprayed with water.
To make 12 tart shells crate 12 square stacks consisting of 8 squares of buttered filo pastry.
Each filo square should measure approximately 14 x 14cm. The filo I used ended up being squarish at 14 x 13cm and it worked fine.
Butter one sheet of filo and fold it in half lengthwise, butter in the centre of the fold.
Cut the filo crosswise into three squares of two layers each.
Repeat with another sheet of pastry.
As you go, stack four of the squares on top each other with butter brushed between layer you stack.
Press each stack of 8 sheets of pastry into the Texas muffin tins as you go.
Centre the stack over the hole in the tin and press in gently. Press the excess pastry to the sides of the tin and gently press into the inner edges of the muffin hole.
Leave the corners of the filo square sitting up over the edge of the muffin tin hole at this stage.