Use bioluminescence. Glow worms are edible and they are phosphorescent. You could make powder from organisms that have phosphorescence (glow worms). Crush them, sprinkle them on top of lollipops or you could try crushing up GloFish:
https://www.foodprocessing-technology.com/features/featureglowing-sushi-experimenting-futuristic-food/ These will glow in a dark room, but only faintly. You can use blacklight to enhance the bioluminescent ingredients response. Here's some nice pictures of fluorescent dye from glowing jellyfish for glow beer using a yeast that responds to "UV or blue light" according to gizmodo. No UV light needed.
Also check out the links at the bottom of that Eater article on glowing beer, glowing udon noodles, and glowing ice cream.
An alternative to food that glows on is own is to use the more commonly available neon colored dyes could look like they glow. These super-bright hues won't give off their own light for a true glow, but will reflect lots of ambient light.
Disney has done a lot of research on making glowing food and they've gone with the LEDs or light-sticks inserted into food. The effect is food safe and dependable, or else they wouldn't use it: Disney's InfinityAide or Fairy Floss or LightSaber Churros Perhaps bake your pie in two pieces and then drop a glowing light cube inside your lemon filling and then plop on the pre-baked top? Or maybe make a crust that has holes in it that you can poke a few small lightsticks into.
The most common way to get a glow in the dark effect is to use UV (fluorescent dyes) because many food safe ingredients (such as tonic water and caramel) respond to UV wavelengths. The UV causes the ingredient to give off its own light (fluoresce). However, I'm not sure if the quinine from tonic water will survive baking. Lots of websites show people using tonic water on their cup/cakes after covering them with jello, like this one https://www.youtube.com/watch?v=qTh4K9Jmh0g There is research about them at Rutgers. Apparently these edible fluorescent food colors are routinely added to food or pharmaceuticals: Allura Red, Sunset Yellow, Brilliant Blue, Fast Green and Tartrazine, a yellow-colored dye. Read more about fluorescent food dyes at: https://phys.org/news/2015-02-fluorescing-food-dyes-probes-quality.html#jCp
Anyway, you could avoid UV and go for blue light. Some things that will flourescen under UV will respond to blue or purple LED light.