For the Cherry Jam:

1. Mix Ingredients: In a saucepan, combine cherries, sugar, and water. Heat over medium until the cherries soften and the mixture begins to simmer.
2. Thicken Jam: Create a slurry by mixing corn starch with a bit of water. Stir this into the cherry mixture continuously until it thickens, about 5-7 minutes.
3. Cool: Remove from heat and let cool to room temperature. The jam will thicken more as it cools.

For the Yogurt Cake Batter:

1. Oven Preparation: Preheat your oven to 180°C (350°F). Prepare a 9-inch cake pan by greasing and flouring it, or lining with parchment paper.
2. Wet Ingredients: In a large bowl, whisk egg yolks, powdered sugar, melted butter, vanilla extract, and yogurt until smooth.
3. Dry Ingredients: Sift flour, baking powder, and salt together in a separate bowl.
4. Combine: Gradually mix the dry ingredients into the wet, stirring until just combined. Be careful not to overmix.
5. Bake: Pour the batter into the cake pan and bake for 25-30 minutes, or until a toothpick comes out clean.
6. Cool: Let the cake cool in the pan for 10 minutes, then move to a wire rack to cool completely.

Assembly:

1. Layering: Slice the cooled cake horizontally to create two layers.
2. Jam Filling: Spread the cherry jam over the bottom layer.
3. Top Layer: Place the second cake layer on top of the jam.
4. Serving Suggestion: Optionally, dust with powdered sugar before serving.

This revamped recipe offers a harmonious blend of moist, yogurt-infused cake and rich, fruity cherry jam, ensuring a delightful dessert experience. Enjoy crafting this exquisite treat!