Preheat the oven to 347°F (175 °C), lay out 2 trays with baking paper. Put the oats to toast for 8 minutes until they release their aroma. In a bowl, beat the butter and sugar until you get a creamy and smooth mixture (about 2-3 minutes). Add the egg and vanilla extract and mix to homogeneity.
In a separate bowl, combine the flour, baking soda, salt and cinnamon. Add the flour mixture to the liquid one and mix until the flour is absorbed. Add the oats, dried fruit or chocolate chips. Shape large cookies with a thickness slightly less than 0.5″ (1 cm) and a diameter of about 2″ (5 cm) with wet hands. Arrange them in a tray and even them out with your fingers if necessary.
Bake the oat cookies with nuts and fruits for around 15 minutes. They must be dry at the edges, but moist in the middle. Leave the cookies in the tray for a few minutes, before transferring them to a bowl.