Add the gel colouring

• Put the buttercream in a bowl.
• Add a generous amount of gel based red food colouring — you need quite a lot depending on the amount of buttercream.

Activate the pigments

• Use an immersion blender to blend the colouring into the buttercream until the pigments are fully activated and the colour is even.

Deepen the shade

• Add a bit of black gel food colouring to the coloured buttercream.
• Blend again to get a nice, deep shade.

Alternative method (optional)

• Melt a small amount of coloured buttercream in the microwave and add it back to the rest.
• Note: this method affects the texture and the cream might get too soft.