Place the flour, sugar, yeast and cinnamon in to a bowl. Make a well in the centre of the mixture and add the eggs, milk and butter and mix until combined. Remove from the bowl and knead the dough on a well-floured board until the dough is smooth. This should take about 5 to 10 minutes. Then place in an oiled bowl, cover in cling wrap and place in a warm spot for about 30minutes or until the mixture doubles. Remove from the bowl and knock the mixture back (re-knead it). Then roll the dough out and cut into doughnut shapes using a doughnut cutter.
Heat some oil in a deep pot until hot. Place the doughnuts in the pot one at a time cooking on each side until golden, and cooked through.