Thaw the frozen blueberries, then mash them with a fork or potato masher.

Add the mashed blueberries, active starter, 190 g water, maple syrup, flour, salt, whole blueberries, and sugar to the stand mixer bowl that’s been fitted with the dough hook. Mix the ingredients on low speed for 5 to 10 minutes, until a smooth dough forms.

Add the remaining 20 g water a little at a time as the dough mixes. You may not need all of it. The dough should feel firm and just slightly tacky.

If the dough is sticking heavily to the bowl or your hands, mix in a little more flour, 1 tablespoon at a time, until it's easier to handle.

Cover the bowl and leave it on the counter overnight, about 8 to 12 hours. By morning, the dough should be noticeably puffier and close to doubled in size.

Divide the dough into 12 equal pieces. I divided mine into 126-gram portions.

Roll each piece into a smooth ball, then poke a hole through the center with your finger. Gently stretch the hole until it's larger than you think it should be. The dough will spring back and the hole will shrink as the bagels rise.

Place each bagel on a small square of parchment paper.

Cover the bagels and let them rise for 4 to 6 hours, or until they look puffy.

Heat your oven to 425°F.

Bring a large pot of water to a boil and stir in the sugar. (Don't add baking soda to the water. It can react with the blueberries and turn the bagels a greenish color.)

Boil the bagels a few at a time for 1 minute on each side. If a bagel sinks instead of floating, it's not ready yet. Put it back on the tray and let it rise a little longer before trying again.

Transfer the boiled bagels to a baking sheet and bake for 15 to 20 minutes, or until they're lightly browned. If you're using an instant-read thermometer, the inside should reach 205 to 210°F. I also turned my bagels over at the 10-minute mark so the bottoms could brown as well.

Let cool completely before eating.