
This silky-smooth Blue Moon Lime Tart has changed how I make desserts forever with its eye-catching natural blue shade and zingy lime taste. It brings back memories of lazy summer days, but doesn't use any of the fake stuff you'd normally find in Blue Moon ice cream.
The first time I whipped this up, my family couldn't believe that algae created such a gorgeous blue color. These days, they beg me to bring it to every family get-together, surprised that something so pretty can actually be good for their bodies too.
- Vegan cookies: They make our fast crust happen – pick ones with a mild taste that lets the filling shine
- Vegan butter: Holds everything together and makes it rich – don't go cheap here
- Coconut milk: Gives us that dreamy, smooth filling – grab the full-fat can for extra luxury
- Blue spirulina powder: Our color wizard that works without changing the flavor – get the real stuff for the prettiest blue
- Fresh lime juice: Cuts through sweetness with a tangy kick – squeeze it yourself for best results
- Agar powder: The plant-based way to make our tart hold its shape – make sure it's pure for proper setting
- Agave syrup: Adds sweetness without taking over – put in more or less depending on what you like
- Vanilla extract: Brings everything together with a hint of warmth – skip the fake stuff
Making It Happen
- Get That Crust Ready:
- Smash those cookies into tiny bits until they look like damp sand. Getting this texture right means your crust won't fall apart when you cut it later. Mix in the melted vegan butter until you've coated every little crumb and it sticks when you press it together. Push it firmly into your pan, making sure to get the corners and edges just right. Pop it in the freezer for 15 minutes to harden up before you add the filling.
- Fix Up the Lime Part:
- First, stir the agar powder into cold coconut milk until it's all mixed in. This keeps lumps away for a nice smooth finish. Warm it up until it bubbles gently for exactly 2 minutes while you keep stirring. Don't cut this time short – the agar needs those full 2 minutes to work its magic. Take it off the heat before adding your lime juice and sweetener to keep that fresh flavor. Pour it over your cold crust and let it chill until it's just firm but still a bit sticky on top so the blue layer sticks to it.
- Whip Up the Blue Part:
- Start by mixing your spirulina with room temp water until it's totally smooth. Take your time here since those blue bits can bunch up if you rush. Make your coconut milk base with agar just like you did before. Wait until it's off the heat to add your blue mixture – this keeps both the color bright and the good stuff inside the spirulina working. Pour it very slowly over the lime layer, using a spoon to break the fall so you don't mess up your pretty layers.
- Let It Set:
- Stick the whole thing in the fridge for at least 2 hours. During this time, it'll firm up and all the flavors will get friendly with each other. The texture changes from soft to perfectly sliceable as it sits. Before serving, let it hang out on the counter for 5-10 minutes so the flavors really pop.

Blue spirulina has become my go-to for creating desserts that make people stop and stare. My kid refused to try this tart at first because she thought anything this blue must be full of fake colors. After I told her it was actually colored with a superfood, she took a tiny bite and couldn't believe how tasty natural ingredients could be.
Keeping Your Blue Moon Tart Fresh
This beauty stays good in the fridge for up to four days if you keep it in something airtight. The colors stay bright and it doesn't get soggy or weird. I've noticed it actually tastes better on day two after the flavors have had time to mingle. If you need to make it way ahead, just cut it into slices, wrap them up tight, and freeze them for up to a month. Let frozen pieces thaw in your fridge overnight and they'll be almost as good as fresh.
Colorful Superfood Swaps
What's so cool about this dessert is how easy it is to change up the colors with different natural powders. Try using pink pitaya for a hot pink version that tastes exactly the same. Matcha gives you a calming green tart that's perfect for Easter or spring parties, while turmeric creates a sunshine yellow treat. Each powder brings its own health perks but keeps that yummy lime flavor. For birthdays and holidays, I often make three mini tarts in different colors for a treat that's both pretty and packed with good stuff.

Ways To Serve It Up
Fresh berries go perfectly with this tart, matching both the taste and the eye-catching color. I usually add a small spoonful of whipped coconut cream on top for some textural contrast and to bring out the coconut flavors in the filling. If you want to get fancy, thinly slice some lime, brush it with agave, and dry it out for see-through lime chips to put on top. The tart also looks amazing at the center of a brunch table when you put some edible flowers around the edges.
Frequently Asked Questions
- → How does it get its blue shade?
The tart's bright blue hue comes from natural blue spirulina powder, which is extracted from special algae.
- → Can I switch up the crust?
Sure! Feel free to try options like almond oat crust, hazelnut pastry, or even crushed Oreos. Just make sure the crust is fully cooled for the best result.
- → How do I use agar powder properly?
Stick with 100% pure agar powder. Fully dissolve it in your liquid and boil it as directed on the packaging to get a perfect set.
- → Can I swap blue spirulina for another shade?
Of course! Try beet powder for red, turmeric for yellow, or matcha for green to make your tart suit your style.
- → How long should the tart chill?
Cool the lime layer for about 1 hour. Once you add the blue layer, chill it for 2 more hours until firm and ready to slice.