Preheat the oven to 185 °C (365 °F). Prepare 12 paper liners (ideally tall ones) and place them in a muffin tin.
In one bowl, sift and mix the all-purpose flour, rice flour, baking powder, and salt.
These cakes are popular throughout Portugal and can be found in every 'pastelaria'. The rice flour gives them a specific, slightly chewy yet moist texture, different from common muffins.
Essential for an authentic Bolo de Arroz is the use of special tall paper liners, often sold already in the shape of these cakes. Just before baking, the cakes are sprinkled with coarse sugar, which forms a crunchy caramelized layer.
Preheat the oven to 185 °C (365 °F). Prepare 12 paper liners (ideally tall ones) and place them in a muffin tin.
In one bowl, sift and mix the all-purpose flour, rice flour, baking powder, and salt.
In a second, larger bowl, whisk the eggs and sugar until the mixture is lightened and fluffy (about 5 minutes).
Reduce the whisking speed and mix in the lemon zest and milk.
Gradually and gently fold the dry ingredients (flour mixture) into the wet mixture until just combined (do not overmix).
Finally, fold in the melted butter.
Divide the batter evenly into the 12 prepared paper liners. Fill them about 3/4 full.
Liberally sprinkle each cake with coarse granulated sugar.
Bake in the preheated oven for 25-30 minutes, or until golden and a skewer inserted into the center comes out clean.
Remove from the oven and let cool on a wire rack. They are best when warm, but can be stored at room temperature.