Preheat oven to 400°F (205°C). Lightly grease your rectangular muffin pan (I use a silicone mini loaf pan) or line with parchment strips for easy removal.
In a medium saucepan, combine milk, oil, sugar, and salt. Heat over medium until steaming (not boiling).
Remove from heat and add tapioca, cassava, and almond flour all at once. Stir vigorously until a smooth, thick dough forms.
Return to low heat for 1–2 minutes, stirring constantly, until the dough pulls from the sides and becomes glossy.
Transfer to a bowl and let cool 3–5 minutes so the eggs don’t scramble.
Beat in eggs gradually, stirring well after each addition, until the dough is smooth and pipeable. It should resemble thick choux pastry.
Spoon or pipe into the rectangular pan cavities, filling each about ¾ full.
Bake at 400°F for 10 minutes to create lift.
Without opening the oven, reduce temperature to 350°F (175°C) and bake another 15–18 minutes, until golden brown and puffed.
Turn off oven, crack the door, and let them cool inside for 10–15 minutes to prevent collapse.
Remove and cool slightly before glazing.