• Preheat the oven to 350 ℉ / 176 ℃.

Make polvoron crust

• Whisk together toasted flour, whole milk, white sugar, and salt. Mix in melted butter.
• In a parchment-lined baking sheet, transfer the polvoron dough and spread it out evenly. Press down with your palms to shape the crust.

Make Calamansi Filling

• In a mixing bowl, whisk together the sugar and flour.
• In another bowl, gently whisk the eggs to break up the yolks while minimizing bubbles. Stop as soon as the eggs are evenly scrambled. Mix in calamansi juice.
• Pour in about 1/3 of the egg-calamansi mix into the dry mix. Use a spatula to mix until well incorporated. Pour in the rest of the liquid and gently stir.
• Strain the mixture into the baking sheet. Hold the strainer at a low height to minimize splashing.
• Use a toothpick to pop any large bubbles.

Bake the Calamansi Bars

• Bake at 350 ℉ / 176 ℃ for 25-30 min until the center has just set. Remove from the oven and let cool completely on the counter.
• Refrigerate for 2 hours to overnight.
• Transfer to a cutting board. Slice, dust with powdered sugar, and serve immediately.