Is an Oreo Cookie blizzard a pure substance or a mixture. If a pure substance is it an element or a compound. If its a mixture state if it is a homogeneous or heterogenous?

A pure substance is made of only one type representative particles. They could be atoms or molecules. In case of elements, the representative particles are atoms and in case of compounds, they are molecules.

A mixture contains two or more representative particles. When the mixture has uniform composition, it is called as homogeneous mixture and when the mixture does not have uniform composition, it is termed as heterogeneous mixture.

Oreo cookie blizzard is made by mixing crushed cookies with ice cream. Here we can see 2 different representative particles, one representing cookie and the other representing ice cream. Therefore it's a mixture. The composition of the mixture is not uniform as solid chunks of cookies can be seen in semi solid ice cream. Therefore it is a heterogeneous mixture.