Lightly grease an 8x8-inch baking dish (adjust number/size of pan if altering batch size), or line with parchment paper. Alternatively, line with foil, but still add a bit of non-stick spray or vegan butter to ease serving.
For the crust, add softened butter and sugar to a mixing bowl and beat until light and fluffy in texture - 1 minute.
Add flour and salt with mixer on low and mix until combined - it should be crumbly.
Add almond milk and mix once more - it should form a cohesive dough. If not, add a bit (1-2 tsp) more almond milk.
Transfer dough to prepared 8x8-inch baking dish and dust the surface with flour. Use your hands to press the dough into the dish until flat and uniform.
Chill in the freezer for 15 minutes, then preheat oven to 350 degrees F (176 C).
Bake crust for 20-25 minutes, or until golden brown on edges and light golden brown in the center - you want it fairly well done. Let cool, but leave the oven on.
In the meantime, prepare filling. Add all filling ingredients except almonds to a small saucepan over medium heat. Vegan butter and chia seeds are optional (to add flavor, richness, and thickness). Cook, stirring/mashing the berries, for about 6-8 minutes or until the filling is bubbly and resembles pourable blueberry jam.
Remove from heat and pour over the baked crust. Top with slivered almonds and bake for another 24-28 minutes, or until filling is bubbly along the edges and almonds are slightly golden brown.
Let cool completely - about 2-3 hours (or overnight) before serving.
Before serving, prepare glaze by adding organic icing sugar to a mixing bowl. Slowly whisk as you add in almond milk 1 Tbsp at a time until a semi-thick, pourable glaze is formed.
Once bars are cooled, drizzle with glaze (optional), loosen the edges with a knife and slice into 9 even bars (amount as original recipe is written // adjust if altering batch size). Serve with a spatula. The first bar can be a bit tricky to get out, so be gentle.
Leftovers keep covered in the refrigerator for 3-4 days, though best when enjoyed within the first 24 hours.
*To speed softening time, cut butter into 1/4 inch slices. *I haven’t tested this recipe with anything other than vegan butter, but you could try coconut oil (as I'm sure people will ask). In that case, I recommend using refined coconut oil at a “spoonable” texture rather than liquid. However, I can’t guarantee the outcome using this ingredient. *I have not tested this recipe with gluten-free flours. But if you try it, let me know how it goes! *Crust adapted from Ina Garten. *Recipe inspired by my friend Arleigh. Loosely adapted from Everything Nothing Wonderful. *Prep time includes chilling and cooling. *Nutrition information is a rough estimate calculated with almonds and glaze.