This can be done via ingredients or treasures.
• tap ingredients
• tap the ingredient you want to extract magic powder from
• tap on the ??? Extract button
• confirm you want to extract
• tap treasures
• tap the treasure you want to extract
• tap ??? Extract
• confirm you want to extract
• tap ingredients
• tap evolution treasures
• Select evolution recipe
• tap extract at the bottom
• choose either from ingredients or from treasures
• tap all the ingredients/treasures you want to extract from
• tap extract magic powder
• tap ingredients
• tap evolution treasures
• Select evolution recipe
• tap on a treasure you CAN'T evolve
• bottom right shows the ingredients needed for the evolution.
• tap the plus sign
• tap make ingredient - providing you have enough magic powder it will make the ingredient and put it into your ingredients list