Line an 8×8-inch baking pan with parchment paper, leaving extra overhang on the sides for easy lifting of the finished bars.

In a medium bowl, combine the graham cracker crumbs, melted butter, granulated sugar, and a pinch of salt. Mix thoroughly until the texture resembles wet sand.

Press the crumb mixture firmly and evenly into the bottom of the prepared pan to form the crust. Place in the freezer for 10 minutes to chill and set.

In a large bowl, beat the softened cream cheese until it is completely smooth and free of lumps.

Add the Greek yogurt, honey (or maple syrup), vanilla extract, lemon juice, and powdered sugar to the cream cheese. Beat until the mixture is creamy and perfectly smooth.

Divide approximately 1/4 cup of the plain white yogurt filling into each of three small separate bowls. Add 1-2 drops of a different gel food coloring to each bowl (e.g., turquoise, pink, yellow) and stir until the colors are vibrant and uniform.

Evenly spread the remaining plain white yogurt filling over the chilled graham cracker crust. Spoon random blobs of the colored fillings on top of the white base.

Using a toothpick or a butter knife, gently swirl the colors through the white base in figure-eights or loose circular patterns. Be careful not to over-swirl, as this can muddy the colors.

Cover the pan tightly with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, until the bars are completely set.

Once set, lift the bars out of the pan using the parchment paper overhangs. Place on a cutting board and slice into 16 equal squares using a sharp knife.

For cleaner cuts, wipe the knife blade with a damp cloth between each slice. If the bars seem too soft to cut neatly, place them back in the freezer for 10-15 minutes before attempting to slice.