Have the flour on a working surface and form it into a mound. Make a well in the centre.
Add the cubed butter to the centre of the mould. Stir the salt into the water and pour inside the flour well.
Work the ingredients with your hands, knead for 6-7 minutes. A firm ball of dough should form, do not add any water to soften the dough as it should be quite hard.
Cover the dough with a tea towel and let rest for 20 minutes. In the meantime, prepare the filling.
2. Venison filling
Set a skillet on medium heat and melt the butter. Finely dice the onion and add it to the pan. Sauté 3-4 minutes.
Add the meat to the pan and stir to distribute the heat evenly. Add the cinnamon, thyme and salt. Cook the meat on medium-high heat until it looks cooked through, 5-6 minutes.
Pour in the red wine and stir until evaporated. Remove the pan from the heat.
Stir in the ground hazelnuts and let slightly cool while you roll out the dough.
3. Assemble and bake
Stretch and roll the dough ball to form a long cylinder. Cut out portions of it that are about 40-45 g. Roll out each dough portion with a rolling pin to 2 mm thick.
Have a pastry circle in one hand and add about 1 1/2 tbsp of filling.
Lightly wet the edges of the pastry circle. Fold the circle in half, to create a half-moon shape encasing the filling inside.
Press egdes together and secure them by pressing them between your fingers or with the prongs of a fork against the working surface.
Place empanadas on a baking tray lined with baking paper. Lightly beat an egg and brush some eggwash on every empanada.
Bake the empanadas in the preheated oven at 180°C (360°F) for 25 minutes or until golden brown.