Masa harina custard
This masa harina custard bun floated to the surface of my brain during a slow bakery week. I became obsessed that week with making a custard thickened only with masa harina and eggs. I also wanted to avoid cornstarch in order to show all that masa harina could be and do on its own. This meant that I needed to learn more about how masa harina thickens, and what custard needs in order to thicken.
During the nixtamalization process, the starch in corn goes through a transformation. Cornstarch is a pure starch, which is why it is used so often in custard-making – it does the job of not only thickening, but protecting the eggs from curdling. The starch in masa harina has changed dramatically by the time it gets to us in two pound bags at the grocery store. This meant that if I was going to use masa harina in a custard, it would need a little help. I still didn’t want to use cornstarch because I knew we’d be baking the custard with the buns and didn’t want it to bake up with a jelly-like texture and consistency.
The next best thing was simply all-purpose flour. A single tablespoon of AP flour took the custard from its many flops as either slightly curdled or very badly curdled, to exactly what I wanted – smooth (albeit some grittiness remains since masa harina is gritty by nature) and luscious. Since those starches in masa harina had been weakened from the nixtamal, the eggs basically stood no chance before the addition of flour. But now? On the custard’s fifth and final test? With the flour acting as protection for the eggs, with the masa harina doing its job as thickener and bringer of flavor? At last, the custard was a success.
To me, this custard tastes like a tamale that needs more time in the steamer. Soft, luscious and big corn flavor with the supporting character of a generous amount of vanilla bean paste (use extract if that’s what you have).
Whisk the masa harina and AP flour into the sugar before adding the sugar to the egg yolks for the custard. This helps the dry ingredients to avoid clumping and helps them to dissolve properly as the custard cooks.
IF the custard is seeming like it’s curdling in the saucepan, remove the pan from the heat for a few moments while continuing to whisk the entire time. Then set the pan back on the stove and continue to whisk, whisk, whisk for 1 minute or so after you notice bubbles forming near the center of the custard. The bubbles mean the starch in the flour has been activated and means your custard will set properly.
The biggest mistake I ever make with custard is adding the hot milk too fast into the egg mixture at the start. You want to whisk in the milk in a very slow, thin stream. Some would say painfully slow (me, I would say this). But whisking the milk in very slowly is your first chance to get a beautifully smooth custard that didn’t curdle. Take the time.
Masa Harina Custard
Yield: about 1 1/2 cups
210 grams (about 1 cup) milk
77 grams (4 large) egg yolks
55 grams (1/4 cup) cane sugar
18 grams (2 tablespoons) masa harina
9 grams (1 tablespoon) all-purpose flour
1 tablespoon vanilla bean paste or 2 tablespoons extract
57 grams (4 tablespoons) unsalted butter
2.5 grams (1/2 teaspoon) kosher salt
Make masa harina custard:
In a 2 quart saucepan, warm the milk just until steaming.
As the milk warms, add the egg yolks to a medium mixing bowl. In a smaller bowl, whisk together the masa harina and flour into the sugar; add to the egg yolks and whisk once more to combine. The egg mixture will be thick.
Temper the egg mixture with 1/3 of the warm milk now, slowly drizzling in milk as you whisk, whisk, whisk simultaneously. Once about 1/3 of the milk has been slowly added, transfer mixture back into the saucepan. Whisk custard constantly over medium-low heat until thickened and bubbles form on its surface, about 10-12 minutes. Don’t be tempted to raise the heat so the custard thickens faster – if the heat is too high, it will almost guarantee your custard to curdle.
Once custard has thickened, remove from the heat and transfer back to the bowl. Stir in the cold butter now and carefully taste the custard (it will be hot). Add salt and additional vanilla, if you want more vanilla flavor.
Press plastic wrap to the surface of the custard so it doesn’t form a skin, and place in the fridge where it needs to chill for at least 8 hours, but preferably longer. The custard can be made up to 48 hours in advance.