In a medium bowl, whisk together 2 cups mochiko (sweet rice flour), 3 tbs granulated sugar, 2 tsp baking powder, and 1 tsp salt until evenly combined.

Combine wet ingredients

In a separate bowl, whisk 2 large eggs until homogenous. Add 1 cup milk and 1 tbs whole milk or cream, 4 tbs melted butter (cooled slightly), and 1 tsp vanilla extract. Whisk until combined.

Make batter

Pour the wet ingredients into the dry ingredients and stir until smooth and no large lumps remain. The batter will be thicker than wheat-based muffin batter but should be pourable. If too thick, add up to 2 tbs additional milk, 1 tbs at a time.

Optional matcha swirl

Reserve about 3/4 cup of the batter in a small bowl. Sift 1 tsp matcha powder into the reserved portion and whisk until fully incorporated and evenly colored. This creates a green swirl batter.

Portion batter into tins

Fill each liner about 2/3 full with plain batter (about 2 tbs per cup of a 12-muffin yield; adjust as needed). Drop about 1 tsp of sweet red bean paste (anko) into the center of each filled cup, then spoon a tablespoon of matcha batter over the top (or plain batter if not using matcha) to cover the filling. Gently tap the tin on the counter to settle the batter and remove large air pockets.

Bake

Bake in the preheated oven for 16–20 minutes, rotating the pan halfway through, until the tops are lightly golden and a toothpick inserted near the center (not into the anko) comes out clean or with a few moist crumbs. Because mochiko keeps moisture, avoid overbaking which will dry the crumb.

Cool

Remove muffins from the oven and let cool in the tin for 5 minutes, then transfer to a wire rack to cool completely (about 30 minutes) before glazing. Cooling helps the texture set and prevents glaze from sliding off warm muffins.

Glaze, fillings, and finishing

Prepare white chocolate glaze

Place 4 oz finely chopped white chocolate in a heatproof bowl. Warm 3 tbs heavy cream in a small saucepan over low heat until it just begins to steam (do not boil). Pour the hot cream over the white chocolate and let sit 30–60 seconds, then stir until smooth and glossy. If needed, return to very low heat in short bursts to fully melt and combine. Stir in 1 tsp yuzu or lemon zest for brightness.

Make black sesame accent

In a small bowl, stir 2 tsp black sesame paste (or tahini) with 1/2 tsp warm water to loosen to a pipeable consistency. Optional: fold 1 tsp powdered sugar if you want it slightly sweeter. Reserve a small piping bag or zip-top bag with a corner snipped.

Glaze the muffins

Place cooled muffins on a wire rack over a sheet pan. Spoon or drizzle about 1 tbs of the white chocolate glaze over each muffin, letting it gloss over the top and drip slightly down the sides. Work quickly while the glaze is still warm and fluid for a smooth finish.

Pipe sesame and finish

Using the prepared sesame paste in the bag, pipe a small dot or swirl in the center of each glazed muffin to highlight the red bean filling beneath. Sprinkle each muffin with a few toasted black sesame seeds and a light dusting of powdered sugar (if using). For an extra touch, lightly dust 1/4 tsp kinako over some muffins for a nutty finish.

Serve or store

For best texture, serve at room temperature within 24 hours. Store leftover muffins in an airtight container at room temperature up to 2 days, or refrigerate up to 4 days. If refrigerated, bring to room temperature before serving or warm briefly (10–15 seconds) in the microwave.