Melt butter and margarine in a heavy saucepan. Add the sugar, corn syrup and water.
Cook on medium heat (turn down as the mixture starts to darken) stirring constantly until the mixture reaches 310 degrees (hard crack stage).
Once the mixture starts to turn a light caramel color, start turning down the heat to prevent it from scorching or turning dark too fast.
Pour into a lightly buttered pan approximately 10" x 15". Once slightly set but still very hot, sprinkle milk chocolate chips over the toffee. When the chocolate chips are soft, spread evenly on top of the candy.
Sprinkle with ground almonds. Cool and break into bite size pieces.
Store in an airtight container