If cake is uncut, slice into thin 1/2-inch horizontal layers. Spread a very thin layer of jam between all but the top layer (optional). Re-stack, wrap in plastic, and chill for 10 minutes.

Using a serrated knife, cut the chilled cake stack precisely into 1-inch squares. Arrange squares on a wire rack set over a baking sheet to catch glaze. Chill squares for another 10 minutes.

Prepare the base glaze by whisking sifted powdered sugar, milk (or cream), vanilla, and optional coconut oil until smooth. Divide the glaze into separate small, warm bowls. Color each bowl with gel food coloring to desired shades (white, pink, lavender, etc.)

One by one, use a small fork to dip each chilled cake square into its respective glaze, ensuring full coverage. Let excess glaze drip off, then place back on the wire rack to set. Repeat for all squares.

Let the glazes set completely at room temperature (15-20 min) or in the fridge (5-10 min) before decorating.

For line art: Mix extra powdered sugar and milk into thick paste. Load into contrasting small piping bags. Pipe thin, parallel zig-zag lines across set petit fours (e.g., white on pink, pink on white). Let set.

For sugar crust: While a second glaze coat is still wet and tacky, dip the top surface into fine sanding sugar (pink, clear, or purple). Let set.

For sprinkled: While the second glaze coat is still tacky, lightly press sprinkles into the top surface. Let set.

Ensure all decorations are set before serving or storing in an airtight container at room temperature for up to 2 days.