Beat the Eggs and Sugars: In a large mixing bowl, crack 2 large eggs and add 90 g of fine sugar along with 8 g of vanilla sugar. Beat the mixture using a hand mixer or whisk until the eggs are pale and the sugars are dissolved, about 2-3 minutes. This helps incorporate air into the mixture, giving the cookies a light texture.

Add the Oil: Slowly pour 90 ml of oil into the egg-sugar mixture, continuing to whisk. The oil will make the dough soft and pliable. Mix until the oil is fully incorporated, creating a smooth batter.

Incorporate Cornstarch: Gradually add 100 g of cornstarch into the wet mixture. The cornstarch helps create a light, crumbly texture for the cookies, giving them a melt-in-your-mouth feel. Stir until fully combined.

Add the Flour Gradually: Begin adding about 300 g of flour in batches. Start with 200 g and stir it into the dough using a spatula or wooden spoon. Continue adding flour until the dough comes together and is no longer sticky. You might not need all 300 g depending on your dough’s consistency, so add the flour gradually.

Add the Pinch of Salt: Don’t forget to add a pinch of salt to balance the sweetness and enhance the flavors.

Knead the Dough: Once the flour is incorporated, knead the dough gently until smooth. The dough should be soft but firm enough to hold its shape when rolled out.

Preheat the Oven: Preheat your oven to 350°F (180°C) and line a baking sheet with parchment paper.

Form the Cookies: Take small portions of the dough (about a tablespoon) and roll them into small balls between your palms. If you want to add jam, use your thumb or the back of a spoon to create a small indent in the center of each ball.

Add Strawberry Jam (Optional): If using strawberry jam, spoon a small amount (about ½ teaspoon) into the center of each indentation. The jam adds a delicious fruity contrast to the rich vanilla cookie.

Place on Baking Sheet: Arrange the dough balls (or thumbprint cookies) on the lined baking sheet, leaving space between them as they will spread slightly during baking.

Bake the Cookies: Place the baking sheet in the preheated oven and bake the cookies for 12-15 minutes, or until the edges are just turning golden brown. Keep an eye on them to ensure they don’t overbake—these cookies should remain soft and light in color.

Cool the Cookies: Once baked, remove the cookies from the oven and allow them to cool on the baking sheet for a few minutes. Transfer them to a wire rack to cool completely. The cookies will firm up as they cool but should remain soft and tender inside.

Serve the Cookies: Once the cookies are completely cooled, they’re ready to serve. You can dust them with powdered sugar for an extra touch of sweetness, or enjoy them as they are. These cookies pair perfectly with a cup of tea, coffee, or a glass of milk.