01 - Combine warm water and sugar in a small bowl. Sprinkle yeast over the surface and let stand for 5 minutes until foamy and activated.
02 - Whisk flour, salt, and cinnamon together in a large bowl. Pour in the yeast mixture and melted butter. Mix until combined, then knead by hand or with a stand mixer for 8–10 minutes until smooth and elastic.
03 - Divide dough evenly into three portions. Add purple gel coloring to one portion, green to another, and yellow to the third. Knead each portion separately until the color is uniform throughout. Wear food-safe gloves to prevent staining.
04 - Place each colored dough portion in a separate bowl, covering with plastic wrap or a clean towel. Let rise for 1 hour until doubled in size.
05 - Roll each colored dough into ropes approximately 12 inches long. Braid one rope of each color together by twisting gently. Form into a bagel shape, pressing the ends firmly to seal. Repeat with remaining dough to make 8 bagels total.
06 - Arrange bagels on a parchment-lined baking sheet, leaving space between each. Cover and let rest at room temperature for 20 minutes until slightly puffed.
07 - Preheat oven to 425°F. Arrange oven rack to center position.
08 - Bring a large pot of water to a rolling boil. Stir in honey or sugar. Working in batches of 2, carefully drop bagels into boiling water. Cook for 1 minute per side (2 minutes total). Remove with a slotted spoon and drain on a wire rack.
09 - Return boiled bagels to the parchment-lined baking sheet. Bake for 18–22 minutes until deeply golden brown and cooked through. Transfer to a wire rack and cool completely before glazing.
10 - Whisk powdered sugar, milk, and vanilla extract in a small bowl until smooth. Adjust consistency with additional milk if needed—glaze should be thick but pourable.
11 - Drizzle vanilla glaze generously over each cooled bagel. Immediately sprinkle with purple, green, and gold sanding sugars while glaze is wet to ensure adhesion.