Season the steaks with Garlic Pepper Seasoning and press seasoning in well. Coat with olive oil. Leave to stand at room temperature.
Adjust the oven rack to the middle position and preheat the oven to 200°C. Line a baking tray.
Beat the egg yolk with the sugar and salt. Cut the pastry squares. Lightly brush pastry tops with egg yolk. Place pastry on baking paper and then on to the baking sheet.
Bake for 10 minutes until golden brown. Remove from oven.
Pan-fry oiled steaks in a non-stick frying pan to medium rare. Remove from pan and cover lightly with foil, shiny side against the steak to reflect the heat back while the steaks are resting.
Use the same pan to make the sauce. Sauté the onion, pre-seasoned with Green Onion Seasoning, in the butter and oil mixture over medium heat until soft and beginning to colour. Add the mushrooms and stir-fry over high heat until just before the mushrooms start drawing water.
Add the brandy, switch off the overhead cooker fan and remove the pan from the stove. Light the brandy, wait for the flames to die down. Add undiluted Beef Stock. Add our Ready to Serve Mushroom Sauce, bring to the boil and season to taste with Garlic Pepper Seasoning. Stir in the thyme.
Split the pastry squares in half horizontally with a serrated knife. Place the bottom half of each pastry on warmed individual dinner plates and spread with chicken liver paté. Position a steak on top. Spoon the Mushroom Sauce over the steaks, top with the remaining pastry, and serve. Garnish with fresh thyme.
When brushing the pastry with the egg yolk, do not allow it to run down the sides of the pastry as it will stop the pastry from puffing up. It is a good idea to trim the pastry again before baking to make sure the edges are clean. Brushing with egg yolk gives the pastry a better colour. Freeze the egg white to use in scrambled eggs or to make meringues.