The proliferation of Cloud Computing platforms has led to the emergence of a large number of heterogeneous platform resources, services, application programming interfaces and supported frameworks and technologies. On one hand, supported frameworks vary from one Platform-as-a-Service (PaaS) to another depending on their implementations and capacities. On the other hand, each PaaS provides a specific and proprietary scenario to provision adequate resources and to deploy applications. In this paper, we propose a new PaaS-independent approach to provision in a unified way, appropriate PaaS resources for applications deployment in Cloud platforms. Our approach aims at addressing vendor lock-in restrictions and applications portability issues in existing Cloud platforms. To that end, we define a unified description model based on the Open Cloud Computing Interface (OCCI) core model that allows describing and managing an abstract Cloud resource. Our defined model consists of two main parts: (1) an OCCI platform extension which describes PaaS resources that can be provisioned by a PaaS to set-up an appropriate environment and (2) an OCCI application extension which describes application resources to deploy an application in this environment. We show the feasibility of our approach with an implementation and a use case of a realistic deployment scenario in Cloud Foundry PaaS