Rich, soft buns delicately spiced with warming chai flavours.
Heat milk and water until just warm/body temperature. Pour into bowl of stand mixer (or large bowl). Add sugar, stir to combine, then sprinkle over with yeast.
Measure and melt butter; measure flour, salt, and spices into a small bowl. Gather remaining ingredients.
Ensure yeast is alive and active (it should look foamy after several minutes; if not, you might have to replace it with fresh yeast). If the yeast looks good, add salt, aquafaba, melted butter, vanilla, and flour mixture, and raisins to the bowl with the liquids. Stir (use the dough hook if using a mixer, the handle of a wooden spoon if doing it by hand) until well combined. Knead with a mixer or by hand for three to ten minutes (less if using a machine, longer if by hand). Dough will be quite sticky.
Leave dough in bowl; cover with a plate or something to keep dough from drying out. Let rise in a warm place until doubled in size (about an hour and a half).
Once risen, turn dough out onto floured countertop and press into a flat circle. Cut circle into 12 even wedges (start by cutting circle in half, then in quarters, then cut each quarter into three equal portions).
Grease a 9 x 13 pan (line with parchment paper if desired).
Form each wedge into a smooth, tight ball, tucking edges under and taking care to make sure raisins are encased in dough (any that are exposed will burn). Place in prepared pan, evenly spaced, making four rows of three.
Cover with an inverted baking sheet or a piece of plastic wrap. Let rise until doubled, about 45 minutes.
About 30 minutes into the second rise, preheat your oven to 375 degrees.
When buns are risen, brush the tops with aquafaba and bake for 20 - 25 minutes (22 is perfect in my oven).
While buns are baking, make icing for crosses. If you want a little extra boost of chai flavour, add a pinch (about 1/8 of a tsp) each of cloves, cinnamon, cardamom, and ground ginger to the icing. You want the icing to be pipeable, but fairly stiff, so the crosses don't run off the tops.
Melt your extra butter, and measure maple syrup.
When buns are baked, remove from oven and brush tops with melted butter right away. Give it a minute or two to soak in and then brush with maple syrup.
Remove buns from pan. Parchment paper makes it easy to lift them out, but you can also use a spatula to lift one side and then slide them out onto a cooling rack.
Allow buns to cool for 5 - 10 minutes. While they're cooling, put the icing into a piping bag that has been fit with a flat tip about 1/4 of an inch wide (the icing will melt slightly, so a round one will work if that's all you have).
While the buns are still quite warm, but not hot, add the crosses. Starting at one end, pipe a line across the middle of each row of buns, once in each direction, until each bun has a cross across the top.
Allow buns to cool a little longer (if you can stand it) and enjoy.
If you'd like to serve these for tea any time of year, you can either omit the icing crosses entirely, or just drizzle across the tops instead of doing crosses.