To make the sponge: In the bowl of a stand mixer, mix all the ingredients together with a wooden spoon until well combined. Cover with plastic wrap, transfer to a warm area and allow the sponge to rise until tripled in size with lots of bubbles, about 3 hours.

After the sponge has fermented, add the remaining flour and the diastatic malt powder. Using the dough hook attachment, mix on medium-low speed until the dough starts to come together. Sprinkle in the salt and continue to mix. You'll need to mix the dough for about 20 minutes, so set a timer. The dough should be smooth and elastic at this point. Cover the bowl with a damp kitchen towel and allow the dough to rest for 15 minutes.

Line a baking sheet with parchment paper and lightly spray with nonstick coating. Using a scale, portion the dough into 130g pieces and place them on the baking sheet and cover with a damp towel so that the dough doesn't dry out. Working with one piece of dough at a time, shape the dough into a tight ball. Cup the dough under your rounded hand, and working in tight circles on a work surface, roll until the dough is smooth and the seam on the bottom is sealed. Return to the baking sheet and cover with a damp cloth. Let the pieces rest for 10 minutes.

Using a damp finger, poke a hole through the center of the dough ball and enlarge the circle so that the bagel is about 4 inches in diameter with a hole that is about 1 1/2 inches. The hole might look large, but the bagels will swell when they rise. Transfer the bagels to the greased baking sheet and cover with plastic wrap and refrigerate overnight.