Spread the bread with an even layer of Marzipan Butter, cover liberally with Homemade Sprinkles and cut each slice into 4 triangles.
In a food processor, blend the almonds, scraping down the sides of the bowl occasionally, until creamy and spreadable, 10 to 12 minutes. Add the powdered sugar, almond extract and salt and blend, scraping down the sides occasionally, until very creamy and spreadable, 12 to 15 minutes more. If desired, drizzle in a tiny bit of oil to thin out the texture and make it more spreadable. Caution: The mixture will be quite hot when it’s finished blending.
Line a baking sheet with parchment paper.
In a small bowl, whisk together the powdered sugar, egg white and salt. The consistency should be slightly thicker than glue. Add a bit of water if it is too thick or more powdered sugar if it is too thin. Divide into three bowls (it won’t seem like that much in each bowl!) and add the food coloring. Transfer each color to a piping bag fitted with a very small tip and pipe lines onto the parchment paper. Let dry at room temperature for 4 hours or overnight. Scrape the lines off the paper and break into sprinkles.