Step 1: In the bowl of a stand mixer fitted with the whisk attachment (or a large bowl with a hand mixer), combine the sifted powdered sugar and meringue powder. Mix on low speed for 30 seconds to combine.
Step 2: Add the warm water, vanilla extract (if using), and almond extract (if using) to the sugar mixture. Beat on low speed until combined, then increase to medium-high speed. Continue to beat for 5-7 minutes, until the icing is very stiff and glossy, forming firm peaks. The mixture should hold its shape when you lift the whisk.
Step 3: Cover the bowl with a damp cloth or plastic wrap touching the surface of the royal icing recipe immediately to prevent it from drying out. This royal icing recipe dries very quickly!
Step 4: To achieve different consistencies, slowly add small amounts of water (a teaspoon or drop by drop) to portions of the royal icing recipe. For outlining consistency, the icing should flow slowly and hold its shape. For flooding consistency (10-15 second count), the icing should smooth out within 10-15 seconds after a line is drawn through it.
Step 5: If desired, add gel food coloring to achieve your desired shades. Start with a small amount and mix well before adding more. This royal icing recipe takes color beautifully.
Step 6: Use immediately for decorating. Store any leftover royal icing recipe in an airtight container with plastic wrap directly on the surface for up to 2 weeks in the refrigerator. Rewhip briefly before use.