Preheat your oven to 170°C (340°F) and line your cupcake pans with liners. In a large mixing bowl, combine sunflower oil, extra-large eggs, and sugar, then beat with an electric mixer on medium-high speed for about 4 minutes until light and fluffy.

Sift together the self-raising flour and salt in a separate bowl. Gradually add this dry mixture to the wet ingredients, mixing gently until just combined. Pour in the milk and vanilla extract, stirring until smooth.

Fill each cupcake liner two-thirds full with batter. Bake for 12 to 15 minutes or until a toothpick comes out clean. Cool for 5 minutes in the pan before transferring to a wire rack.

For the salted caramel filling, melt white granulated sugar over medium heat, whisking continuously. Once melted, stop whisking and allow it to turn an amber color for about 8 to 10 minutes. Be cautious to prevent burning.

Whisk in the heavy cream carefully and then add room-temperature unsalted butter. Stir in the sea salt and pour the mixture into a jar to cool.

Beat powdered sugar and unsalted butter together until fine crumbs form. Add room-temperature cream cheese and blend until smooth. Mix in half a cup of cooled salted caramel.

Cores each cupcake and fill with salted caramel. Frost the tops with the creamy caramel frosting and sprinkle with salted caramel pieces.